gethashespersec is 0 so bitcoin-qt doesn't mine
I don't know what that is supposed to mean.
But this from your OP says differently
Avg. Hash Rate - 315 Gh/s
WU - 4658
Difficulty Accepted - 0
It says you are mining as you have a hash rate and a Worker Utility. The Difficulty Accepted will be 0 until you find a share that meets or exceeds current difficulty which would be a block finding share.
What is your Best Share: ?