Alright, let's piece together what we learned from the latest episode, to the 6 suspects.

The recorded session mentions that Red John is middle aged and Healthy. We can eliminate Smith and Stiles right away from this. I would also say Bertram and McAlister as well, but that depends on your definition of middle aged.

I think that one episode with Kirkland really sealed him not being Red John, when he killed someone that knew his identity. He would have recognized him. I honestly think Kirkland wants to kill Red John, that's why he is trying to figure out who he is as well.

At this point,  I think it's Haffner. He just seems like the last "Logical" one left. I honestly thought it was going to be Partridge though, and we saw how that turned out. It was also very creepy how he visited her, and it personally seems like he was toying with her, since he knows that Jane gave her the list of suspects.

There is some more Evidence that needs exploring, like the whole nurse and "Carmen Lee" thing, this episode.