Alright, So I can definitely say that Red John is NOT Robert Kirkland.At this stage we know that Robert Kirkland is involved in something but we don't know what! In fact i believe that he might not even be involved with Red John. Think about it this is not the last season and it would be WAYYYYYY to obvious if he was in fact Red John. Heller and co. want to 
keep us guessing and on our feet, therefore we can def. say that Kirkland is NOT RED JOHN. Now it remains to be seen if he is or is not involved with Red John. I do no believe so.

I think as this season comes to an end we will find out what and who Robert Kirkland is/works for.