There is no evidence that the robotic surgery has better results than "traditional" open surgery. (The incision for open surgery is much smaller now than in was 20 years ago.) Robotic surgery costs about two or three times as much, and requires significantly more time under anesthesia. And in fact there are some ways in which it can be inferior: for example, if the tumor is near the nerve bundles, a skilled surgeon can literally feel with the fingers whether there is likely involvement, while the robotic surgeon simply cannot tell. (Prostate tumors are not visible or detectable on scans.) It can be easier for the surgeon in the open method to biopsy lymph nodes, etc. I'm not saying that robotic surgery is bad, I'm just pointing out that use of highly expensive technology does not make it superior. In both cases, it is likely to take several hundred procedures before the surgeon is operating at peak expertise.
From what I've learned, radiation instead of surgery is most likely to be chosen for a patient who is not well enough to withstand surgery. Radiation, like all other therapies, has progressed, but it is definitely not superior in terms of avoiding side effects and complications such as incontinence and impotence, and can very likely have added complications as a result of unavoidable damage to the rectum and bladder and other surrounding structures. It is also impossible to address possible lymph node involvement with radiation.
The age of your friend probably has little to do with his prognosis. The stage of the tumor has everything to do with it. There are well-established statistical scales based on tumor stage and PSA. There is an enormous amount of information available online through Johns Hopkins.
My H, an extremely fit 56 yr old, had prostate surgery in March. He just received the results of his first post-op PSA: negative.