Hello, the way steemit works is a little bit complicated, so bear with me while I try to explain it.
As of right now, it takes 7 days to get paid. A lot of the articles are older. The amount of money people get from an upvote depends on the upvoters steem power. Generally, the best way to get more steem is to comment or post. The people that have millions of steem power are called whales, as a single upvote from them could give you dollars. Of the amount listed as a possible reward, 50% of it will be able to be withdrawn instantly (as steem/steem dollars) but the other 50% goes into your steem power that can be withdrawn weekly over the course of two years, but also gains interest at a very fast rate.
In general, resteeming does not give you any steem or steem power.
If you have any questions, please feel free to ask.