here’s where u can see who subscribed :
1. Sign in to YouTube.
2. Go to your Subscribers List by clicking Creator Studio and then Community and then Subscribers.
(https://www.youtube.com/subscribers)
3. You can find your total number of subscribers at the top of the page. The list shows only subscribers who have chosen to share their subscriptions publicly.
4. You can sort the list by Most recent or Most popular using the drop-down menu in the top right.