What is a pronoun for the word Dad?

If it is used as a name, as in talking about your dad, then it is capitalized.

Examples : "Yes, Dad is going to cook today." "Tomorrow is Dad's birthday."

If you are using it as a placeholder, or describing a relationship, do not capitalize it.

Examples: "My dad is going to cook today." "He has to ask his dad for permission." "Jerry is Bill's dad."