I read online a 1.4 Litre engine with turbo is about the equivalent of a 2.0L without turbo how true is that? ?

It completely depends on the boost pressure that you run.  That being said, while it's really not your question it may be relevant: a naturally aspirated engine is often a whoooole lot more reliable than a turbo'd or supercharged one.

Back in the 80s F1 cars had 1.5l turbo engines that made over 1000bhp in qualifying, about the same as a Spitfire’s Merlin engine from 1940., so anything is possible given enough money.

you could probably wind up the boost so it makes as much power and torque as a 3 litre engine but how long its going to last is the problem.

HP may be close but torque curve is completely different.

I have a 1.0L turbo Focus - the 2L Zetec (both newer models 2018 ) has about 35+ hp more and I am certain much more low end torque. My 2000 Focus 2l zetec had only about 10hp more than my newer one liter.

Configuration is key - SOHC vs DOHC etc. 

Depends on the specific engines involved. For example If you take the Fiat 1.4L Turbo from the Jeep Compass makes 177 HP.  The 2.0L (petrol) engine from the Ford Focus makes about 160 HP.  So in this case the 1.4L Turbo is a bit more powerful. But compared to the S2000's 240 HP 2.0L engine, the 1.4L Turbo is not nearly as powerful. 

There is more than one way to design an engine and displacement alone does not dictate how much power the engine will be able to create.

Only if they have the same power and torque output.