I can't find the link but I saw once that one of his higher profile interviews only had like 200,000 viewers...total. He has some of the lowest ratings on CNN. I doubt he will be around much longer.
edit: this is nt the exact article, but dropping from 521,000 viewers in the 24-35 demo to now only getting 39,000 is bad news
http://www.telegraph.co.uk/sport/football/teams/usa/9361012/Piers-Morgan-brings-worst-ratings-to-CNN-prime-time-slot-in-21-years.html