Here is what the US Constitution says:
Article II, Section 2
1: The President ... shall have Power to grant Reprieves and Pardons for Offences against the United States, except in Cases of Impeachment.
So, I guess he CAN pardon himself unless he is impeached.
But I don't think it would be wise to do such a thing. It's not even a good idea to talk about doing it.
He should do what Pat Buchanan suggests - resist the subpoena, do NOT answer any questions, and dare Congress to impeach him:
The only institution that is empowered to prosecute a president is Congress. If charges against Trump are to be brought, this is the arena, this is the forum, where the battle should be fought and the fate and future of the Trump presidency decided.
You can read the rest @
Or resign, and let Pence pardon him.