There is no limit. Casinos who bar people from playing generally do it for bad behavior. Card counters can get banned from playing certain games, but this isn't nearly as common as people like to believe, mainly because the effectiveness of card counting isn't as great as people believe.
So, you won't get banned as long as you're a legitimate player on a real winning streak. That said, casinos do need to protect themselves. So, if they suspect that a consistent winning streak is due to something like card counting or even cheating, they may ban you.
