This is definitely different for every sport, so I think it is hard to make a general statement. So, I will attempt to answer the question from the point-of-view of fantasy football and the NFL.
There is evidence to show that it actually hurts ticket sales. In 2012, the NFL will require that teams show fantasy statistics at all stadiums. The belief is that fans are staying home to keep track of their fantasy football teams instead of buying tickets and attending games. Since ticket sales have been on the decline* for the past 5 years or so and subscriptions to services like NFL Red Zone and NFL Ticket are on the increase, it would stand to reason that the increase in popularity does not necessarily mean an increase in ticket sales. While this may be good for the NFL, it is not good for the individual clubs.
It is worth noting that this impacts the NFL harder than other sports due to the fact that at least 50% of their games are played at 1:00PM ET on Sundays. So, if you are attending a game, you are likely missing out on the majority of other games going on that week. The impact may not be nearly as severe with fantasy baseball or fantasy basketball.
*: warning- article is dated 2010, but the 2011 data was skewed due to the lockout and the 2012 data is not yet available