Steam doesn't release their sales numbers, so nobody tracks digital sales, and nobody disputes that these account for a greater proportion of PC sales relative to physical sales than for the consoles, but nobody knows by how much. However, you can cross-reference this website:
http://steamspy.com/
PC (Steam) = 437,669 total digital owners
That's all-time, not just a week's sales, and that's current to today. If we look at VGchartz tracking for the consoles total sales (which only goes through July 25th):
PS4 = 2,358, 704 total physical sales
XB1 = 890,969 total physical sales
PC = 78,286 total physical sales
So you can see that even if we add these figures together the PC is getting crushed in total sales, and that only addresses volume. Steam tends to pitch sales on games, even newer releases, far more often than physical console copies are sold at a discount. That's less revenue for developers/distributors, resulting in lower profits, and that makes the platform even less attractive to them.
Furthermore, the problem is that VGChartz doesn't tracks digital sales at all (neither for PC nor consoles) since they depend on retail samples from third party vendors who are willing to share that information, and over the past few years, especially, users have increasingly purchased their games more and more via the digital stores on consoles. Nobody has any clue where that pie chart stands, currently, but I think digital console sales constitute a huge chunk of sales, today (possibly approaching the majority of sales). It's just so much easier than going to the store. You click a button, and a game downloads. The bandwidth of the average user caught up and can handle this delivery system. Most can download a game in several hours to around a day. So we are simply once against comparing apples to oranges.
That being said...the PC is still competitive for some multi-platform games against the Xbox One. The best example for PC is
GTA V:
http://www.dsogaming.com/news/repor...games-sell-better-on-the-pc-than-on-xbox-one/
3.3m for PC vs. 3.6m for the Xbox One. We also glean some insight into PC hard copy sales vs. digital sales (at least for this one game): 75% of PC owners bought it digitally. So that should give you an idea of what the Steamspy figures are representing: a significant majority of total PC sales.