Quora's terms of service allow for republishing[0] of any amount of content posted after April 22, 2010, so long as the user didn't mark it as not to be republished. There are a few caveats around attribution and a requirement to update content on request if Quora's copy changes, but it's actually fairly liberal.

0: https://www.quora.com/about/tos (search for "Quora's Licenses to You")