Following head injury and brain damage it is difficult to predict about the extent of memory loss. As the swelling comes down the brain will regain back it's functioning.
Till then as a family please don't try to test his memory often by asking him "tell who?Where?When?" This would either irritate him or will push him to depression.
Next Steps
give him news papers, keep wall clock and calender on his room. update him with latest news, introduce ppl by their name and other personal information.
Health Tips
Keep a look on his mood, temper and keep the consulting doctor informed.