There are various ways that you can earn money with Hubpages:
With the Hubpages Ad Program, you get paid once your balance reaches $50. Once you have been paid, your balance returns to $0 and you have to wait until your earnings build up to $50 again and then you get paid again.
The other way to earn is with Google Adsense. I live in the UK and I get paid everytime my balance hits £60 (not sure what the US$ amount is).