I want to know about the benefits of joining theatre and is there any earning

Well Anuraag if you're keen on acting surely joining theatre would give you the requisite experience. And if you turn out to be good you can head for TV Serials and get some roles. Alternative career for actors is also animation, since it is about acting too. Here you play the role of an actor-direc

Theater is confined to some metropolitan cities like Mumbai and Chennai and it should find a gretaer propagation. In the olden days , there was more encouragement and patronage. It all depends on earning money to survive .So, assess carefully before making it a full-time profession.