Of course you can make $ as an affiliate, or the system wouldn't be in place. AaliyahLove.com wouldn't be half as successful as it is now, without all of the traffic and sales my lovely affiliates send me.
How successful you are depends on how much traffic you have, but more importantly, what KIND of traffic you have. You need target the right kind of traffic for the right kind of websites or it won't convert, and you won't get any sales.
I know plenty of people who make over a thousand dollars a month doing affiliate sales. But it's a lot of work, and it's a daily job. Just like anything else, the more dedicated you are and the more time and effort you put into it, the more money you will make.