Far too much.
Uh, not according to the link KP put up. You couldn't get me out of bed for most of those salaries, and I'm an underpaid educator!
An average for freelancers is $26k? Yikes.
I can see why they all suck. No legitimate journalist would go near those numbers.
It should be noted that freelancers have some other kind of income(according to the link), and you would need to as well with those peanuts. Then there is the whole unpaid interns thing zor brought up, which arguably drives the average lower. The staff wages aren't much better unfortunately, and you get what you pay for, evidenced by the glorified bloggers currently staffing these sites.
Unfortunately, said bloggers do have more power than some dude on WordPress, and I can see how a hit-piece or negative **** dump can severely affect the reputation of a dev, game, or studio. That isn't to say we should bar any ideology from criticising games, but a separation between reviews and opinion pieces would be nice.
All of this is pretty irrelevant though, YouTube personalities will probably dominate the reviews market and professional printed reviews will go the way of the typewriter. I personally welcome this, as I find footage of gameplay to be much more informative than some hipster in a tiffy about Bayonetta's bewbs or that the game needlessly encourages violence.