That all depends on the pair. It depends on how many eggs the female releases, how well the male takes care of the eggs, how strong the fry are when they hatch. All of these things determine how many fry will survive based on the fish.
As long as you do daily water changes, feed the fry properly, and make sure that they are all growing up healthy and strong then you should be able to keep all of the once that are meant to live alive.
Remember though, you have to be ready to dispose of any fry that have bent spines because there is no point letting them live if they will be in pain. It is better to put them out of their misery while they are still young, before you get overly attached.