Well we call people who offer space on the storj network farmers. For now, payments are made monthly using a pretty complicated formula, based on both shared data (data you upload back to the renters), data uploaded to your machine (we call it a node). For now, files are mirrored a few times to other nodes (which isn't paid for now). Farmers are getting about $35USD/TB/month shared currently.

Over time as the network gets more stable and more users, I know that the storj team might implement microtransactions as well as the ability to pay for more mirrors. When that happens, subsidized payments will probably stop and payments would probably be below $5/TB/month since a renter only pays $15/TB/month