NO SPOILERS

I watched the leaked episode just now and I believe it's the episode that will air on Sunday, just like I believed Red John was on the list of seven.
The reveal was underwhelming for me and I have to admit I didn't really enjoy the episode. There were a number of ludicrous things that happened there so I do hope it was a fake, but somehow I doubt it.

Nothing was explained except the explosion, and that is very disappointing as fans would like to know. If Red John dies without giving an explanation, as it happened in the leaked episode, then we will never know as no one can explain it but him.

Two things don't add up for me: 1. the character that turned out to be RJ wasn't really a red herring in my opinion (as the actor suggested in the article), and 2. there was talk of two of the three 'deceased' suspects coming back, which didn't happen. Those two things give hope that it may be a fake, but then I don't see why they'd do that. What's the point? It's the ultimate Red John episode, people will watch it anyway, you don't need to tease. If anything, this will bring ratings down as some of us who watched the leaked episode will consider it to be the real deal and won't tune in on Sunday. There won't be many, but there will be a number of people who will do that and in my opinion it can only increase the dissatisfaction and decrease the number of viewers for the official airing. This is why I don't believe CBS would, for some odd reason, air a fake episode. And if they wouldn't do it (makes no sense to me), then it really was leaked, in which case the reveal is genuine and it's ruined for many.