My dad has pancreatic cancer that has spread to his liver. chemo did not help. how long can he live without further treatment?

Multiple factors: Multiple factors determine survival from here onwards including his baseline status (eg karnofsky performance scale), clinical status including breathing status, apetite, weight which would suggest median survival less than 60 days and supportive care and pain management. Usually oncologist will give you a best case scenario, in his case it could be 30 to 90 days. My prayers for your dad.

Months, maybe: Sorry; that is unfortunately a common presentation for a very bad disease. Since chemo was not successful, it is unlikely that any reatment will cause improvement in the disease. However, treatment may improve symptoms, e.g. Jaundice, pain, obstruction to bowel.

Palliative Care: Survival rates are most appropriately applied to large groups of patients; it's impossible to give such a number for one person, especially without knowing his own unique situation. As a generalization, it is very difficult to completely eradicate cancer in that setting. The fact that he has not responded to chemotherapy would suggest that the focus should be on palliative (comfort) care.

Few months at best: Most pateints with metastatic pancreatic cnacer die within 6 months to 12 months. So given that he has liver metastases and already failed chemo, he may not live more than 1, 2 or 3 months. But it is not possible to predict it exactly.