Yes. Cory's live in schools of 3 and it should be fine and include lots of hiding places and plants. But then again it kinda depends on your betta's personality sometimes it can be so aggressive that it can chase your fish until it gets tired or not notice them at all.
Corydoras are very peaceful fish. They'll live with anything that lives in fresh water. It's the other fish in the tank that may cause trouble. Corys are shoaling fish, not schooling. They prefer to forage with their own kind in the tank, but will eventually pal up with any similar species.
__________________ "Fear not, my young apprentice. Just change the tank water."