Is he or is he not?

"He might be gxx"
"No,he's not."
"But I saw him and he ..."
"No,he's not."
"How do you know?"
"He's just not."
"But..."
And the conversation continues with "he is" and "he's not".
So is he or is he not?
Don't even try to start;
I have no doubt *wink*