Hi purpledinosaur -
The interviews for Theory at the GC are pretty straightforward - What are your research interests/how do you see yourself fitting into the program at the GC - last year they asked someone what text they would use to teach Post Tonal Theory - that might be because they want to see if you would be capable of teaching at one of the CUNY schools.
Just be yourself and know what you want, and also - why you want to pursue a PhD when the economy is in such a terrible state - that was also a question from last year.
It may be helpful to prep yourself by doing some readings in the field to refresh your memory.
I had several friends who applied there last year and got accepted. Hope that helps you!
Good luck!
