if this is regarding adsense, and the amount of hubs needed to make a nice amount of money
it all indeed depends on the amount of hubs, and the topic, as you will notice, that on one hub, you'll gain more money per click as on others.
When you for instance, write a hub about baking cakes, you'll get for instance 0,05$ per click, when you write about for instance, law, injury, measothelioma,;....
You'll get much more per click.
you'll need to look at the cost per click of a keyword in adwords keyword tool, this way, you'll seeth ta one keyword in a certain niche can be only $0,05 worth, while the other can even go to $50 per click.
So it's quantity of hubs+cpc= $$$$