It may or it may not. It depends on the root cause of his sciatica, which can be caused by different things going on inside the body. Sicatica can be stubborn, so you should be realistic about the resutls that can be achieved in one session. He might get lucky - with a very talented therapist it's possible he could achieve significant relief after just one massage. More likely a combination of things would be helpful, including some excercises and/or stretching along with massage. Ice is usually helpful when applied on the low back if it's caused by a spinal condition. Streching and deep tissue massage is going to be more helfpul if it is a nerve imgingement in the deep gluteal muscles including the piriformis.
Visit our website to learn about more benefits of massage and I hope your dad has found or will soon find relief for this painful condition.