Mistake - forgot to subtract non-GT1s, only 77,550.
Updated post: Some calculations from the 2013 Milliman HCV report(link below)
They estimated that 164 million Americans (53%) out of 310 million were covered by commercial insurance.
The express scripts formulary action applies to 25 million, or 15 % of commercial patients or 8% of all Americans. More importantly, the HCV prevalence among commercial patients is only 0.47%. So, the Express scripts would roughly have 117,500 HCV individuals, but only 77,500 would be GT1 patients.