Buckley, the summer signing from Watford, has scored four goals in his last four Championship games including the last-minute winner against Leicester on Saturday, while his deflected shot knocked Newcastle out of the FA Cup last weekend.
"At the moment he is on fire, he is untouchable," said Poyet.
"I said a few weeks ago he had repaid his £1million transfer fee so now he is in credit with us after the last few games.
"He's always there and the balls are falling to him in the right places at the right time. He is creating the chances and scoring goals."