How long typically would a cancer patient have without chemotherapy to live once spread to the liver, after 6 months chemotherapy that wasn’t very effective.. is it worth trying to give another chemotherapy a chance when you have been told it will give you a little longer given the possible side effects?

Thank you

He had removed from bowel in January and recently got a lot better after initial chemotherapy. Second round about to start. In January he also had pneumonia which has since cleared. However cough now returned and bringing up material. Growth on neck and something breaking out on face. Also pains in legs. He is optimistic and a figher.He expects to live for years but I need to know what is realistic.