WOTC does have
their own webshop. But more importantly...
Every single objective indicator we have, indicates that 5e is well outselling Pathfinder right now.
The Amazon Bestseller List.
The Barnes and Noble Bestseller List
The New York Times Bestseller List
The
ICv2 Report of Retail Sales
The
Hot Games List of what RPGs are being discussed on the Internet Right Now
The Hasbro Quarterly Report which (under FTC regulation for accuracy) listed D&D as materially profitable to the company (it's first mention that way ever).
Mearls and Crawford confirming the PHB has outsold the PHB from any other edition on record, with Eric Mona confirming the Pathfinder core book sold less than one of those prior books.
Mass media coverage of D&D by non-D&D sources compared to mass media coverage of Pathfinder.
Eric Mona admitting the entire RPG market was lifted by D&D 5e coming out and describing Pathfinder in terms of a "post-5th Edition paradigm".
There are more but by now I hope I made my point. And most of these indicators were perfectly acceptable to Pathfinder fans when Pathfinder was the game that they were indicating at the time was doing better than D&D, so it would be pretty hypocritical to claim suddenly they're not good indicators now that they are indicating something different.