How do I prevent french toast from deflating after I take it off the pan?

I use a thick bread (I purchase a whole loaf and cut my own slices) and make sure you don't soak it. Hot pan with butter and watch it closely. Takes only a minute or two to cook.

French Toast is not like a pneumatic tire. It can't really deflate. If you are saying that the center sinks back in then try a change of bread to something like a sturdy Multigrain. Other readers may have alternate suggestions.