He is going to have a positive B sample, it is extremely rare that the B sample comes back different to the original sample given.
He is going to serve his 2 years ban, and rightly so.
Wigan should during this period support Gaz, as long as he is showing genuine regret for his actions and is proactive in ensuring that it doesn't happen again, and then after the 2 years if he still wants to come back and play rugby then the club should see where they are at and whether they want him.
I would certainly not be against having him play for wigan again in two years time, as long as the management made special circumstances such as extremely regular drug tests for him, and promises made by him to the club to sort himself out.
HOPEFULLY this will have given him the kick up the ar se that he needed, and will use the two years away from the support to sort his life out [and bulk up to become a prop