What would the life expectancy of someone with end stage renal failure be?

Longevity and ESRD: Patients with esrd live shorter lives than age-matched control without esrd. Their longevity depends on their age when they start dialysis and what other co-morbidities they have, such as diabetes. For a more specific answer you need to supply that information. You can, or course, ask the nephrologist treating the patient you are asking about.

Other factors too!: A lot of other things help explain this. If the person has multiple other medical problems life expectancy could be very short. From my experience most people with end-stage kidney disease have a matter of years on average. Anyone with end-stage disease of any kind should be actively preparing for the end-of-life, creating advanced directives and completing their bucket lists!