Recommendation for upgrading a gaming PC?

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There really isn't much point in upgrading if you're gaming at 1920x1080 and the monitor has a 60hz-75hz refresh rate. If you're gaming at 1440p with a 144hz monitor then an upgrade would go a long ways in delivering better visuals and higher framerates. I finally bought an RTX 30 series card yesterday after a month of trying so it's possible to attain new parts if you're willing to play the game.

The game should run fine on your PC. I'm not sure what you mean by it seems a "little more demanding". Just tone down your settings slightly.

I have a similar system, except i7-8700 and 32gb RAM. Just waiting until 3080s are actually in stock and I am set

I can't recommend anything because there are major shortages of Graphics cards and AMD Ryzen processors. There is also a power supply shortage which has caused power supplies to become overpriced. 

The Core i7-6700 is still alright so I would recommend upgrading the Graphics card first. If you do upgrade the CPU first then all you MIGHT see is a more stable framerate of a higher framerate in some situations. You won't be able to raise the settings unless you upgrade the Graphics card first. The GTX 1070 is just slightly better than the GTX 1660 ti so you'd have to put down the money and go with something that's the same as the RTX 2080 to see a real upgrade. Since the RTX 20 series has been discontinued so you could look at the RTX 3060ti which is a little bit faster than the RTX 2080 Super.

The other reason I'd recommend holding off on a CPU upgrade is you'd have to replace the motherboard and maybe the RAM if you want to upgrade the CPU. The best in-socket upgrade for you would be the Core i7-7700k which isn't much better than the Core i3-10300 or the 6700. Also, since Games are more dependent on the Graphics card performance, you won't see a lineal performance increase by upgrading the CPU. Some games will make you think you wasted you money on the CPU. The AMD Ryzen 5000 processors are the Gaming leader but AMD will probably lose their gaming crown when Intel comes out with their 11th Generation processors. 

I just want to thank everyone here for taking their time to answer this question. Based on all the answers, it sounds like my PC is good for another few years and I agree that I should just build a new system when the time comes, which I don't mind.

Resident Evil 3 is not so bad on my system and Resident Evil 7 was perfect on ultra settings, so I'll just stay with what I have for now.

Thank you so much, everyone!

You can't do much more than to max out your RAM and to put a 4-gig graphics card in your computer.

These games are a marketing trap by now you should have figured that out they entice your mind with a fantasy world drug the game itself and then next year they sneak up the requirements a little bit and then the next year they sneak it up a little more and pretty soon you have to buy a machine to keep up with the upgraded games that they keep throwing at you.

That's what it's all about friend their drug dealers dealing in fantasy world games they get your mind addicted and then you have to go make a physical purchase that's what it's all about

You don't have a lot of options regarding upgrade potential, but here's the rundown of things...

* RAM: NO UPGRADE REQUIRED -- Unless you're shooting for 1440p or 4K (2160p), you should have enough RAM to handle virtually every game.  Unless you're planning to host a server on your computer, any extra RAM would go unused.

* CPU: Upgrade Potential, but not feasible due to architecture -- While your i7-6700 is currently 4 CPU generations old (at time of post), there's some potential with an upgrade to an i7-10700.  This change would give your system a potential 25% boost in performance.  If you have the unlocked version (i7-6700K, as you claim speeds of 4.0 Ghz vs 3.5 Ghz for the locked version), the performance boost drops to around 18% on average.

HOWEVER, the 10th Gen i7 processor has double the cores than your current processor (8 cores w/ HT vs 4 cores w/ HT), so it can multitask a bit better even though the clock speed is slightly slower (maxing out at 3.8 Ghz).  This may require changing your PC's motherboard, which can easily snowball into replacing other components...  so it may not be feasible due to costs & time required to complete this change.

* Graphics Card: UPGRADE POTENTIAL -- While you had a high-end graphics card at the time, it's current 2-3 generations old & the current guideline is that for each generation you go up, you drop one level of effective performance (NOT 100% accurate, but it provides a reasonable comparison)...  So that GTX 1070 = GTX 1560 = RTX 2050 = RTX 3040 (I know RTX 2050 & 3040 don't exist, but humor me here).

If you want to upgrade here, you'll want to jump to RTX 2070 or RTX 3070 in order see a significant performance gain (since the GTX 1570 wouldn't provide the desired performance boost).  HOWEVER, your system might run into some performance bottlenecks with the motherboard.

How you proceed with upgrades is up to you, but this give you an idea on where to focus your efforts.

You could buy a newer graphics card as it's two generations old, but then your almost-5-year-old CPU will be the new bottleneck.

You can't really upgrade a CPU without also upgrading the motherboard, which then you're better off just building a new system.

So your options are to upgrade the video card or build/buy new.

The game should run fine on your PC. I'm not sure what you mean by it seems a "little more demanding". Just tone down your settings slightly.