Actually CNN ratings have been inching up recently, for whatever reason.  Maybe they have a new kitten and puppy YouTube video program on during Primetime.  I don't know whether Fox News can keep the momentum.  The ratings popped because of the blood in the water for the upcoming mid-terms.  Now with control of Congress coming soon, the ratings may sag a little because there is less fire in the belly.
As far "pay whatever", Fox News delivers 105% of what their market viewer wants, but there is very little mainstream support for the channel.  It will never break into the broader market.  A particular person watches Fox News, and it isn't Joe Q. Public who doesn't watch the news much.   He'll watch CNN, when he needs to.  Fox News isn't a general news channel, so while they may beat CNN and MSNBC soundly, their growth is limited to their very specific, but extremely loyal, viewer demographic.