Absolutely! Yes, you earn SC with that, it is called hosting (or "farming" in Sia jargon). Just download the last Sia client, wait until the blockchain is synchronized, go to the Hosting tab, choose your parameters (pricing, drives, collateral) and click on "Announce host". Just be sure to have some SC on your wallet to offer as a collateral (minimum 2000SC unless you use the command line instead of the UI)