While PC gaming will never,ever outsell console units in terms of software. It's definitely far from being dead, which console users absolutely love to scream. Generally speaking, I find it amusing that this topic continues to come up (I remember it being mentioned back in the days of NES).
Anyway, here's a good link to read, after 3 weeks on sale, Witcher has sold 600k copies. While this isnt huge, it's definitely not a small number.