Connection often starts before either person has consciously decided that a conversation is going well. We notice rhythm, posture, attention and whether the other person makes us feel at ease.
Mirror the energy, not every movement
Subtly matching pace and tone can create familiarity. The point is not to imitate him. Stay present, listen carefully and allow your body language to respond naturally.
Use his words
When you pick up an important word or idea he has used and ask about it, you show that you are actually listening. Combine that with open questions and sincere eye contact. The most persuasive signal is still genuine interest.