How long does yeast live after baking?

Yeast dies at about 130-140F.

Bread is done baking at 200F or so.

Almost all the yeast is dead when the bread is done.

Edit
I wrote "almost" because in the context of cooking nothing is ever 100%. Not all alcohol boils it off a sauce. Not all microbes are killed. Etc.

The longer and hotter you cook the more are killed until there are too few to be an issue. We're content if 99.99% of bacteria or yeast are dead - but there are always a few that survive.

As an example- Russian kvass is made by putting well toasted black bread in water with a little sugar until it is carbonated. There is enough yeast alive in the bread even after baking and well toasting.

The thermal death point for yeast cells is 130° F–140° F (55° C–60° C).

Most bread is cooked when the internal temperature reaches 200 F or 100 C.

The yeast is dead.

The most realistic answer, including many correct comments above, is 99.9999..% dead.

Yeast and bacteria can sporulate, and spores can survive very harsh conditions. A spore is basically a solid: a cell which has been dried out, packed with sugars and wrapped in an extra thick cell wall. They are not metabolically active, so they can stay that way for thousands of years. And they can survive boiling temperatures for a little while too, that's why temperatures above boiling are needed for sterilization.

So if any of the yeast in your dough (or bacteria that are in there too) decided to sporulate before the bake, your could find them alive later. But they would not be active just after the bread is baked, the temperature at which they can grow is, as others have mentioned, quite a bit lower than boiling.

I don't know whether baker's yeast actually sporulates much, but it is said that brewers yeast are very unlikely to make spores. Maybe they've had it too easy at the brewery. But I'm pretty confident that after you've baked your bread, there will be more active yeast and bacteria falling onto the outside than there are live yeast on the inside.

BTW - if you used dried yeast from a package, they are not spores, they are actually made be freeze drying live yeast, which is why its so important to rehydrate them with water, as written on the package.

There must be some live yeast in it because that's how they make wine in prison. Store bought bread seems to be a lot doughier though, so maybe that's why. I've never been locked up, but my friends and I were bored and made wine with a couple slices of bread, sugar, and crystal lite; it worked very well.