The global GDP is $126T, a 5% productivity increase would correspond to $6.3T.

So, I have the following thoughts:

How much more productive can AI for knowledge work realistically make the global economy? 5%, 10%, 20%?

What if it also does robotics soon and can be deployed in manufacturing and construction? Can we get 50% more productive, or 200%?

Then there's science, medicine, and so on. Who is to say what happens if AI solves also that?

While I do not know if AI will be capable for these use cases, I see no reason to believe it unlikely that AI could be applicable to eg. robotics and speed up production by factor 3x.