I'm nearly sure, if you combine the looks of a couple of the replays, that his foot did not touch the plate. However, on the replays they were showing on TV at first, it wasn't clear at all. It took them quite some time to get to replay angles that showed it better, and I'm not sure the replay guys really had time to find those, then go through them side-by-side. They had to make a call at some point, and the angles up to then were not too conclusive. I imagine it was a "play stands" call at that point, and the Internet types eventually worked it down to a couple of good angles, side-by-side. The replay guys didn't have the luxury of that time, nor was it presented to them that way.
To me the question of blocking the plate etc. comes into more of should he have been called safe anyways, despite the foot not actually touching. His foot certainly got around the catcher and was over the plate before the tag was made, and was pushed off by the catcher's knee as he slid in to block the plate more (which had nothing to do with the tag, but was I'm sure instinctive after a lifetime of plate blocking).