You'll want to pay attention to:
Engagement (how many people like, comment, and share your content)
Retention (how many patrons keep their pledge to you over time)
Delete surveys (shown to patrons if they delete a pledge, gives creators insight into why they're leaving)
Click-through rate (percentage of viewers who click a link on a post, video, or other content, shows how engaged your supporters are)
Recent post viewers (see how many viewers you have on your posts)