Since 2013 Katy sold 3.5M albums with PRISM. And 30M singles ? Idk
Since 2013 Gaga has sold 3M albums with ARTPOP and Cheek 2 Cheek. And like 8-9M singles ?
This is Katy at her peak and Gaga at her lowest since she started.
Are y'all for real ?

Katy won't outsell Gaga in albums, EVER.
And TEA is the most inaccurate thing ever. Someone listening to the same song 1B times, does not equal someone listening to 12-15 DIFFERENT songs - a whole body of work etc.
It's not even remotely accurate.
You can say that Carly sold 1M albums based on CMM's TEAs alone - which is NOT true, not logical not ANYTHING.