The timelord general and his staff sort of answered it towards the end.
"All twelve of them"
"No sir, all thirteen!"
At least for the Time Lords, Capaldi is the 13th.
Well only because Hurt identified himself as a Doctor on the viewscreen. With the war going on, I doubt they had much time to quibble over the details.
But they were calling him the Doctor earlier in the Episode and so were the Daleks.