I had paraesophageal hernia surgery in December. The surgeon did a nissen fundoplicatian. Is that what your dad is having? If you do a search of my name you'll see some of my accounts. I am 7 weeks post surgery today and I am eating everything and feel normal.
Joy gave you good advice. I didn't have a recliner so I slept in a chair with ottoman and lots of pillows for a few nights. It was impossible for me to lay flat for a while and it took even longer (a month) to lay on my side. Loose clothing are necessary for a while. It's easier for men, I think, because of the bra issue. My surgery was laparoscopic with 5 incisions and 2 of them were right at the bra line. I hope your dad's is a lap surgery and not open as the recovery is much shorter and less painful.
Have a supply of juice, yogurt, cream of wheat, pudding, soup and tea. You never really know how long the liquids and soft diet is necessary. Every patient and surgeon is different. I was discharged on day 2 with orders to eat soft, which the surgeon said meant well chewed pasta, mashed potatoes and well cooked and chewed veggies. I really enjoyed warm tea with honey and saltine crackers chewed well. I had no problem with pills but if you can't get them in liquid, crush them in applesauce. For the first week or so take pain pills regularly so you don't end up chasing the pain. Something else that was a comfort to me was a rechargeable hot water bottle. (from Amazon)
Everyone seems to have different experiences so prepare for the worst and hope for the best. Wishing you and your dad the best!