i assume you want to know what the average per article is. only hp management knows that number. i personally know one hubber who makes payout every month with about 50 hubs. she doesn't use social media to promote her hubs. her traffic is purely from search engines. i believe she is on the more successful end of the spectrum, but you won't see her on the forums acting like a know it all.
the two main things she has going for her are the age of her hubs (she's been here about 6 years) and good topics. she writes about things that people are searching for but don't have a ton of competition. with the niche sites, i believe even a new writer can start seeing non-disappointing monthly income if they consistently write hubs that are selected for niche sites and choose topics wisely. it might take a year before the beer money becomes beer and pizza money. older hubs simply make more money.
the only way to know for sure is to start writing and see for yourself.