Position number one means two things. First of all, you will get more visitors, because the majority of viewers searching for the term will go to the first result. I don't know about you, but when I search for something, I usually go to the first, second, or third result. I don't go to page 14 and start looking for results.
Secondly, the top position will give you more "respect". If Google is displaying your website first for the keyword, why would somebody trust a website from page eight more than yours which is ranked first? Knowing that it's ranked first gives you more credit.
But there is no "certain" amount of money you will make. If you are using Adsense, a multitude of factors can affect the overall outcome. If you have a terrible theme, users will be less likely to engage in clicking the ads. If you have no content, they might feel something's "up" and leave. If you have too many ads, people might feel overwhelmed and leave to the next site hoping that it'll be cleaner and easier to understand.
The last factor is obviously the traffic volume. If your keyword generates a large amount of searches, then you will get more traffic, and therefore more clicks on ads. If your keyword only gets 100 searches a month (and let's say, even though it's impossible that %100 of searches click your website) then you're only getting ~3 hits a day, and your chances of monetization are slim.
So hard work, research, and a good structure help it pay off!