Rinne's still comfortably in 1st, but Gibson slots in at 2nd or 3rd (Hellebuyck being the other guy) on my ballot. Realistically, though, after Rinne, there's a field of 5-6 guys who could all campaign for those two remaining nominations.
Gibson's individual stats are actually quite good. He's showing strongly in advanced metrics, and his SV% is 4th among guys with at least 40 games played. (one of them is Fleury, who might fall short due to his lack of games played, and another is Raanta, who plays in hockey obscurity and won't get the recognition he deserves -- also probably going to get snubbed for lack of GP. The 3rd guy ahead of him is Rinne.)
And even by the eye test, Gibson has been one of the best goalies in the league this year. Especially given the fact that our team usually slugs out absolute stinkers defensively.
People look too much at team-controlled statistics like GAA, wins, and shutouts when evaluating for this trophy. If your team can't play defense and allows a crap-ton of shots, your GAA is going to go up. If your team can't play defense and also can't give you much goal support, you're not going to win as much. If you're taking a ridiculous amount of scoring chances against every night (like against the Jets a couple nights ago), then you're going to be hard-pressed to shut them out even if you're at your best.