Russian culture has a long history and tradition and Russians are very proud of it.
Russians consider themselves as a well educated nation. They read a lot, books are cheap, and one can afford to buy 5-10 books a month without serious damage to a family budget.
Russians are also big fond of live performances at theatres and since tickets are affordable (prices in cinemas and theatres are comparable), they enjoy attending theatres: opera, musical, ballet, drama etc.
Usually every city has a few theatres. The theatre culture was developed during the Soviet times when tickets were sold through schools and enterprises: cities were divided into areas and there was a theatre agent responsible for each particular area. The agent would bring tickets for distribution to every enterprise and school in his area and the person responsible for "culture sector" would organize collective visit to the theatre. I think it was an excellent system since people had the opportunity to attend theatres from the early age, starting from attending performances in a Muppet theatre, then moving to the Youth Drama Theatre, then to Drama, Musical and Opera, according to their age. Also attending performances in a company is always much more fun, which contributed to the popularity of theatres. This is how most Russian people have developed their taste for live performances.
Movie theatres are also becoming popular in Russia and they are equipped with the latest sound systems. When Russian people talk about movie theatres, they will usually say "cinema"; if they talk about "theatres", they mean live performances.