can fav exchange helpful for ranking my gigs?
Favourites are a way for real, legitimate buyers to Bookmark your service, to use later. Nobody knows if they impact ranking, but the thousands of sellers with zero sales despite having hundreds of favourites would suggest that they do not.
Favourite exchanges therefore, are a waste of time. But then, you could say that about any attempt to cheat the system.
Your best bet (your only bet) is to provide a genuinely valuable service that’s in demand to real customers. Focus on that rather than ways to trick the system, and you might find success here.