Not the exact word, but he did accuse said staffer aiding terrorist groups. That is the definition in the Constitution: Treason shall consist of making war against the United States, or giving aid and comfort to their enemies...
Is said staffer involved with terrorist?
I don't know. Gaffney, according to two FReepers who were present and listening, didn't present any evidence at the time of the speech. I want to know if he has done so since.