Traffic of course is one of the big determinants of the revenue potential, but in some ways it is the most difficult to control. However, traffic is not the only aspect of making money, some hubs will earn a lot more per thousand views than other hubs.
The topic of the article is also important, some topics pay a lot more than others. Ads are displayed on your hub that match your keywords and some ads are worth a lot more when clicked or when viewed than others. Making money is not the only topic that pays well. The Adwords keyword tool which is free to use, will give you information about cost per click of various keywords. Under the stats on each of your hubs there will also be an estimation of the commercial potential of your hub. Most of my hubs are $$$, which I think is the average, but a few are $$ and a couple have 4$ signs. If you want to have a better rate per thousand views (RPM) you should find out what keywords pay well and target them. This should give you a better revenue per Adsense click or a better payout per 1000 impressions from the Ad program.
I am really bad at getting any sales out of Amazon, but some people make a lot of money from them. I think hubs that are specifically written to get sales from Amazon, either review hubs or ones that describe how to deal with a specific problem that involves buying a product from Amazon are ones that convert well. Just writing an informational hub and adding an Amazon module will probably not result in many sales.