Depends on the personality of the betta, like SaraB stated. Some bettas can get along with companions (I've heard people doing kuhlis) and some bettas can't. My bettas get along well with a variety of other fish in a 72G. I think it also depends on the size of your tank, obviously a smaller space can be more challenging with potentially aggressive and territorial fish like bettas. You could always try it out and keep a watchful eye on everybody. Make sure you have a backup plan in case it doesn't work out- because it truly could go either way.
Platys, Tetras, Mollies, Bettas, BN Plecos
Red Eared Slider