Not a whole lot, unfortunately. He is not practising, so he does not have a trusted relationship with the Church or possibly with anyone and anything connected to it. He needs to have an encounter with Jesus, a conversion of heart to realize what his faith means first for him to want that for his child. Simply giving logical reasons to him at its best would make him do it under force, and so won’t follow up with educating his child in the faith which is required as part of infant baptism, or at its worst, push him further away from the faith.
So what you need to work on is to ask the Lord to teach you how to better evangelize him, as well as begging the Lord to open up ways and send the right people into his life so he may come to encounter the Lord.