The report TwitterMum gives you good steps to build an account of many followers. You can then sell the followers and make huge money or get paid to tweet to it.
If most of your followers are bots, then you'll be lucky to get one person clicking on your site out of 20,000. Your followers should be interactive and should have an interest on what you have to say. If they are interested on weight loss, and your site is about weight loss, then you have a potential sale from that person. Quality is more important than having thousands of bot followers.
yes, you can make money from twitter followers as long as they are targeted to what your promote. Otherwise its just crap.