He is basically assuming that the recent production from Samsung is 100% sold prior to year end. Presumably, this would need to be sold to the US Govt via the OWS program. He is using a price similar to Remdesivir, which I think it $2,300 per patient, or so.
He first quoted this $2 billion potential 2020 revenue figure sometime around July.
I could research the exact number of vials and exact price, but I don't think that NP did, so I really shouldn't either.