There are a couple of ways to earn through Adsense. Some of the ads of calculated on CPM basis, which is per 1000 views, and some on CPC basis, that is cost per click. Typically, CPC ads tend to result in a lot more income. You CANNOT decide which ads is placed on your content, unless you go for section targeting, where advertisers bid for a particular ad unit on a specific position on a webpage.
With Hubpages, the CPC is really low. Google doesn't really like platforms where a large number of authors are allowed to post without much editorial supervision.
Your best bet is to start a website of your own where you will also be able to earn 100% of all the income on it. I have personally seen CPC as high as $15, and know of people who have seen a CPC of even $100!
Yes, you need a lot of traffic to generate money with adsense, especially with Hubpages.