As to a prediction, Gelfand has a worse record against Anand than he does against Kasparov, Karpov, Ivanchuk, and Kramnik. He is certainly capable of playing at the Championship level, but there is no reason to believe he could beat Anand at this time. It would be the biggest upset ever in a title match since at least Tal-Botvinnik 1960, and perhaps of all time, excepting only Euwe's upset of Alekhine.
Gelfand winning the title couldn't well be a smaller upset than Tal's beating Botvinnik. Tal had won the Soviet Championship consecutive years, won Interzonal and Candidates clearly (+12 in 28 games, including 4-0 against Fischer), and faced a 49-year-old Botvinnik. Gelfand's results have been nowhere near those of Tal before the title match, while there were many good reasons to rank the latter as the strongest player in the world at the time of the match.
Euwe winning was of course a big surprise, but his results in the 1930s are often forgotten. Just before winning the title he shared first in Hastings 1934, ahead of Capablanca. The same year he won against Alekhine in Zürich but since he lost against Lasker Alekhine still won the tournament. Euwe's results were good enough for Chessmetrics to rank him as World #2 at that time, and during a five-year-period around the match he is never outside the top three but frequently #1. So to me Gelfand winning the title would be the biggest sensation ever in the history of the World Championship.
it seems anand have a upper edge