These numbers are dependent on so many things. How big the lead single is, how much promo is done or if they release it in an impactful large-scale way (a la Bey), how good the music is, if it's up for streaming... But these are just rough guesses
I think she will tbh. ARTPOP only sold 28k less than PRISM in its first week, and Katy was coming off of Roar! I doubt her lead single will be that big of a hit again. Don't underestimate Gaga, she has a huge fanbase! Katy might surpass her in SPS though...
But the PRISM era also had a few more hits (including Dark Horse which was huge) while ARTPOP fizzled even harder post-Applause. So music-wise Katy's in a better position than she was when PRISM launched while Gaga has it worse
Yes, Xtina now has a huge following due to The Voice, I'm sure she can pull 130,000 sales. But again, Katy's era can go both ways. I do expect Katy to actually go the successful route but still.
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Edit: I doubt Taylor's gonna crack 1 million this time around. I feel like people are viewing her more negatively these days.
if she sticks to her usual release time-table she'll have the new album out in late oct/early nov this year and it will most likely sell 1-1.3 million in pure sales
This is RICH. Taylor has "gotten lucky" 4 times now, each album sells more than the last during debut week, and you think she's gonna decline to less than the album she released when she was 18? MESS. She'll sell double what you predicted and then some.
This is RICH. Taylor has "gotten lucky" 4 times now, each album sells more than the last during debut week, and you think she's gonna decline to less than the album she released when she was 18? MESS. 
She'll sell double what you predicted and then some.