You will have profit from any amount of GHS - after your hashes will pay for themselves (ROI time).
That is not profit but getting the investment back,you can profit if you play the pump and dump game in Gh's market.
To get reasonable amount of BTCs per day you probably need smth like 50 THs of S7
Buying S7 and mining could be profitable if you get any better electricity rates but not the GH's.