He said in an interview that it was technically profitable, but that nobody was taking a paycheck. That was in 2010. It's been supposed that the 'passes' system in 2012 made the site actually-profitable, but I haven't seen any statement to that effect.
He also offered refunds for the passes last year because Google's new Recaptcha system meant that a lot of users were no longer seeing captchas at all.
http://bits.blogs.nytimes.com/2010/03/19/one-on-one-christop...