Most of the characters he plays seem ENFp, especially Rob Gordon from "High Fidelity," but Cusack himself seems very INFp.
Judge for yourselves:
On doing -type things with Hunter S. Thompson (couldn't find many other video interviews with him)
He's a very introspective person; very creative and perceptive about people and relationships, and seems to devote a great deal of time to understanding others, both as an actor and as a person. He's also got the shy, sweet, self-deprecating going on, and describes his thoughts and perceptions in a very abstract, descriptive, contemplative, way. He loves poetic, emotive, creative words too.
The NPR interviewer says of him, "I always believe you have an inner life, like when you're onscreen I always believe that you're thinking interesting thoughts, and that the world is registering on you, and that you're having a dialogue with yourself about the meaning of it and that it's kind of funny... and there are a lot of actors that just don't quite have that, you don't imagine them having an inner life"
His response: (laughs) "They're probably more adjusted."