Finding the number of units sold for CS:GO is difficult since there's no definitive statistic, but
this reddit post states that the month of May 2014 had unique players playing CS:GO, which puts my personal estimate of total sales at approximately 6 million units.
Meanwhile,
Mojang directly tells us that Minecraft has sold 16.8 million units.
Does CS:GO cater to a competitive demographic that has a lot of overlap with MCGamer? Yes.
Will CS:GO surpass Minecraft in terms of sales and cultural impact? Unlikely.