You can raise the fee if it's Replaceable-By-Fee (RBF) or use Child-Pays-For-Parent (CPFP)
CPFP is an available option for him if his transaction has a change in amount sufficient to cover the raised fee, or he is in the full control of the transaction's destination address with enough money on it.
If I were in his shoes , I would wait. These days we have already witnessed fees of less than 5 sats/vbyte.