Expect to lose a good $20,000+ before you start making it (and much more) back.

There's no ads company that'll make you profit from a file host unless you're operating the whole ShareCash shit, where you fill out forms.. have to click on ads.. etc. Banner ads may compensate a percentage of your outgoing funds, but you'll have to rely on other things such as premium account purchases, etc. CPC will be useless for you, and CPM won't get you too far either if your click rate is low; which it will be, as people want their file, not to click for their million dollar visitor prize.

It seems you're starting a filehost to make money from the start, and honestly, you're in the wrong field for that..

For it to operate effectively (economies of scale), you'll need to purchase a few racks to begin, and bandwith in bulk. Sure, this will cost thousands, but eventually when traffic hits you, you'll earn back a lot more in ratio than if you just started with a single server running on a 10TB cap line.