For the amount of visitors and posts we have here, the amount of servers and bandwidth required probably costs $50k-$100k a year.
No idea if there are any paid staff. There's probably a few thousand dollars in annual accounting and legal fees as well.
4chan is still one of the top #1,000 visited sites in the entire world. It's a lot of traffic even though threads are pruned saving space and bandwidth, it's still a lot of people and a lot of posts at any given moment.