This is from a native English movie Present perfect examples from movies (see:0:35)
A: "How long has he been gone?"
B: "2 weeks, 1 day, 15 hours."
I understand that this question is asking about how much time has passed so far after he left. In other words, this is the same as "How long has it been since he went?"
Am I right in my thinking? Or is it asking "How long will he stay where he went?"