I have a good friend who makes over ten k in adsense a month, not with hubpages though. Sometimes he had even $19000 months. I tell you that just to let you know that i really know how much you can make.
Now here, many people who think have a say, kinda stumbled into the money making per accident.
The key is to develop a METHOD that works for you. Write and write a lot. Find a mix between big interest topics that pay a decent amount per click.
Public Interest+Price=Earnings in Adsense.