You've got a lot of space in there, but it would help if I knew what kinds you're putting in there. If you're getting some green emerald cories, I'd say about 5-10 of them. It depends on the cat and the siz, not to mention their temperment.
as of now i have 3 albino cories and i think that i would like to have some more of those or some of the cories with the black stripe that I have seen called "skunk" cories