I will not be surprised if this ends up to be one of the best selling album of this year, if it has televised promo support. Furthermore, Glee is family-friendly, so this should be a great gift for holiday season this year. Things are always unpredictable about Christmas album.

My prediction
First week number: 100k+
By year end: 1 - 1.5 mil

However, I will laugh hard if this flops

Is it released physically or digitally only?

Both. Physical CD is currently #5 on Amazon.

Ow. I think it might sell up to 180k.

Totally forgot about that It is released through Amazon (shipping of physical copies) as well as iTunes, but can someone from the States verifies whether they are selling physical copies?

150-200K

I just checked the Target site. It's available there.