Is it a PPI he's been prescribed? They are very effective if taken often so best to keep up with them if possible - even if he has to set an alarm or something as a reminder.
I was always advised to not put pressure on my tum - apart from keeping weight down, position is important so if he reads in bed for instance, he ought to sit up with his back straight and not reading in such a way that his back would bend mid way (if you see what I mean). He needs to maintain good posture all the time really. No bending forward to use laptop, etc. Also worth not wearing very tight clothing around the abdomen. Some people reccomend tilting the bed as well, by putting books under the head of the bed (ie. the actual frame) so the whole bed is on an angle. If he just sleeps with extra pillows he's only going to squeeze the stomach more and cause more reflux.
Diet wise - avoid chilli, acidic stuff i.e. vinegar, tomatoes, fats, grease, rich foods, peanut butter, alcohol, curries, crisps..
I was told with the worst of attacks to eat a reasonably bland diet for up to a week - e.g. rice, apple juice, apple sauce, mashed potato, root veg, chicken, white fish, porridge, melon, cucumber, dried non citrus fruit etc.
Oh and I can't stress enough - don't eat stuff like milk or mints, no matter how many people tell you they get rid of heartburn. They alleviate the initial symptoms and then make it far, far worse. As far as I know milk only promotes the production of more acid.