We don’t limit the number of followers you can have. However, we do monitor how aggressively users follow other users. We try to make sure that none of our limits restrain reasonable usage, and will not affect most Twitter users.
We monitor all accounts for aggressive following and follow churn (repeatedly following and un-following large numbers of other users). You can read more about these below, but if you don’t follow or un-follow hundreds of users in a single day, and you aren’t using automated methods of following users, you should be fine.
Please note that Twitter does not permit any automated or bulk following or un-following behavior. Please review our Automation Rules and Best Practices for more information on automating your account.