The number of followers for Jessa and Jill were mostly accumulated in the pre-Joshgate days. I think how they are really doing on Instagram is better evaluated by the number of likes their posts receive now. On the last ten picture posts, Jessa is averaging 119,130 likes, Jill averages 34,468.4 and Jinger's average is 86,344.5. In other words, Jill is the least-liked by a long shot.
The number of views on the last five video posts averages 465,400 for Jessa and just 128,597.2 for Jill. (Jinger hardly ever posts videos.)