It really depends on the topic of your site, how the ads are implemented, and basically how Adsense is optimized in your site. In terms of topic, some topics such as dating or gaming — which are both fairly low paying clicks — would need about 100,000 visitors or more per day before they can even earn $1,000 a month. That means to earn about $100K, they would need millions of visitors per month. However, good content sites on small business and entrepreneurship, for example, would need only 400,000 visitors or even less per month and still earn a nice $15,000-$20,000 a month. Also consider the click though rate — huge difference in income can be earned if your CTR is 10% as against 1%.
It is really hard to determine how you will earn from Adsense or even other affiliate programs — the only way is to test it on your site and experiment the best way to showcase the ads that will bring in the most revenue
Popularity: 7% [?]