Benefits/risks of pacemaker if >90?

Small risk-big bene: If a pacemaker is indicated, age is completely irrelevant. The vast majority of people who need and get pacemakers are elderly. It doesn't matter if you're >100. The procedure is minor and done under local anesthetic with minimal risk. If you're symptomatic from a rhythm disturbance corrected by a pacemaker, you will feel much better with it and there's not reason not to proceed.

Risk/benefits : In any procedure the risks and benefits need to be considered. If there is significant risks of falls or of injury to yourself that would be fixed by a pacemaker then it may be worth the risk of it. However, the risk of surgery at 90+ years of age is also significant. Would discuss this with your family as well as your physician.