Heads up, Creators: On Dec 13-14 you may see a noticeable decrease in your sub count as we remove spam subscriptions. If spam is removed, you'll see a YouTube Studio alert: https://goo.gl/qGDBvX This should help give you confidence that the subs you do have are real fans!
There is no auto sub thing, and this is a part of removing fake subs. Pewdiepie also has bots sub to him and spamming the T-Series pages with nonsense comments and downvotes.