There is not a great deal of the ship visible in your photo, but it was certainly taken on the Olympic. The clue is the bulkhead lamp seen beside the person on the left. The position of this lamp differed between Olympic and Titanic.
The date is a bit less certain. I think the ventilator visible between the two men lacks the cowl vent added post-war, so this would put the photo somewhere between 1911 and 1914.
The officer on the left side of the photo bears a resemblance to Olympic's surgeon, Dr. Beaumont. If this is the case, then the photo date would be no earlier than 1912 (when he joined the ship).
I have no idea who the other fellow in the photo is. Maybe the assistant surgeon?