It's all a numbers game with your hubs. The more you have the better opportunity to make more money. For example lets say you work diligently on setting up 200 hubs and get your adsense code rocking on all of them. For the sake of this argument we are going to assume that you get just 50 page views each month for each of your hubs (on average).
This means that for the month you would be looking at 10,000 page views. With just a 2% CTR and a pretty average CPC of 30 cents you wold be looking at $60 per month--with zero costs, making all of that profit. That's a cell phone or utility bill paid for.
It is important to remember that Adsense is not the only way to make money on hubpages. You should sign up for an Amazon Associates account and always-always promote related products in your hubs.