There are so many factors involved that I don't think anyone can answer your question with absolute certainty. However, 70,000 is great and more than enough to make a good income, but it depends on other factors. Also, don't forget visitors. A visitor can click an ad as well as a member.
Quit you day job? Hmmm, not sure. For example, I live in the U.S. and make 4 figures from adsense a month, but I could never quit my day job. Maybe if I lived in another country I could but not in the U.S.
The best you can do is give it a try and see what happens. Don't expect your first try to be successful. You will have to tweak and tweak some more. I have seen webmasters double their income simply by tweaking their adsense code to get the right combination of color, ad size, and ad placement. Trial and error is the only way to optimize your income.
Last edited by db3204 (2010-11-11 13:06:01)