Actually they were around $22,400 according to the comment just under that. Still, I wouldn't be able to tell you whether or not they operated at a loss. You'd have to ask jedberg.
300 million pageviews/month goes a long way. Sure, their CTR is probably lower than most sites, but their traffic is huge.
Let's say their CTR is 0.1%. That's 300k clicks/month. I'm building in some wiggle-room here, as a 0.1% CTR is abysmal, but often their ads aren't really ads. Even at $0.01/click, that's still $30k/month. More than enough for hosting. Now, I'd hazard a guess that most of my numbers are quite a bit on the low side, as reddit has operated for years without CN shutting the doors. Also, from what the admins have intimated from time to time, they make money, but not enough to register on CN's radar.
I wouldn't discount their ad sales; traffic like that carries a lot of weight.
Since then afaik they've added more servers.
> "but they did make enough to stay afloat"
I think Reddit has been operating at a loss for quite some time.