You don't need fake followers in tumblr. What you need is visibility. Since no one can see your followers in tumblr. There no point on getting fake followers.
Think about what you need to do to make your tumblr blog start getting visibility and you could start making a dime...
With the experience I've learnt that tumblr has very concrete requisites (and simple ones) to start getting traffic. If you fail with these requisites tumblr will never drive traffic to your blog, just because they will not make it public.
Just experiment what works, and what not. Then keep/discard.