How much you can make from placing articles and affiliate links on your website differs from person to person. How much you are able to make will depend mostly on how successful your site is. This means getting good search engine rankings through SEO efforts, making your site enjoyable and informative to read through engaging content, building your site around a great niche subject, how big your site is, and how many sites you have.
Some people claim to make as much as $10,000 per month ($120,000 per year) through building and promoting niche sites, however, most people should not expect this kind of success, especially if you are very new, as that kind of success usually only comes with experience and acquired skill. A reasonable income to expect from a niche site, after you have worked for months to gain traffic and are hooked up with good affiliates, may be $500-$1,000 per month. However this is recurring income, so you will make that much monthly off of the efforts you put into that one site, it is not a one shot deal.
After you have a successful site, most choose to continue to build niche sites. The more sites that you build, the better an income you can...