Please don't fall for these theories that claim they've seen the Red John episode, it hasn't been leaked, no one has taken it, and Red John's identity will be safe till Sunday. Those who've really seen the episode have signed a confidentiality agreement, and they won't reveal Red John's identity or the plot.
I believe it all started from these spoiler sites where the writer gave some remote clues as to what we can expect from the Red John episode. These people keep ornamenting those points, and post them as theories. Others just take these theories, add their sick fantasies and come up with new theories. Sick fantasies I've seen before. It's their old ideas added to the current context of the show, nothing more.
I like the way some of them say "it's not been leaked", "it's been taken from the source code of the website", as if that even means anything!!!
Another interesting point is they all claim they know who Red John is but in order to avoid spoilers they won't tell you. Other than that, they reveal literally anything about the next episode.

Don't waste your time searching for a link to the Red John episode. There is none. And if there is, it is fake.