I had my male betta live with many many kinds of fish over the 3 years I have had him. Poor guy had it rough.
I kept him with a breeding pair for angels. He lived just fine in fear. I never saw him he always hid in a plant out of sight out of mind.
My betta has a 10 gal tank to him self well there are some neons in it that he like to boss around. Since I moved him to his own place he is 100x happier.
I kept this guy with tetras,angel, gourami, blue acara, rams, keyholes, plecos, corys ,and yes discus. He has lived in a 5 gal, 36 gal, and 80gal. The 10 gal is the best tank for him. Well a 20gal long would be great. That said I can say yes bettas can live with many kinds of fish but they will not be happy. They are best kept in a tank made for them. If you want to fully enjoy bettas keep them alone or with fish like Cory cats or neons.