There were quite a few open GI spots after last year's match -- I suspect that had more to do with programs not understanding that they needed to rank ~5-10 people per open slot they have. I expect this year there will be very few open spots after the match. Last year in Cardiology there were 2-3 open spots not filled by the match.
No matter what happens, any open spots will be filled quickly. By "quickly", I mean within 30 minutes or so, probably less.
Your best chance of getting one of those spots would be to have your Program Director / GI Fellowship PD (if your program has one) / Medicine Chair / GI Chair call programs on your behalf. Those are the calls that fellowship PD's will take seriously.