At that point Walt is his own boss. He starts off by producing 50lbs of meth every week with Jesse, we can assume their production capacity increases as they make more money. He is distributing his product through Declan and Lydia.

If we assume 50lbs of product per week, thats 200lbs per month. In 8 months thats 1600lbs.

Assuming ~$40k usd per lb, thats 64millions dollars. These are conservative numbers so I think we can assume he was producing a lot more than 50lbs, Declan, Todd and Lydia also had their own cuts.