Can e-commerce businesses make money primarily through banner advertisements?

You can make money through banner ads and other affiliate strategies on websites,

The key is the traffic to your website, reputation of your website (pagerank) and your clickthrough rate from adsense or other advertisements

Example:
website with 10000 visitors per day, 5% clickthrough rate and an average of $0.50 per click would generate you a revenue of 5% of 10000 = 500, x $0.50 = $250 dollars per day

This is just through adsense if you add other affiliates to your site like amazon context links and commission junction banners you could possible average about $400 dollars per day!

The trick is your traffic, which can be hard to generate

Source(s):

http://en.wikipedia.org/wiki/adsense…

http://zebracommerce.com