Sorry to hear about your dad.
Do you know if the encephalitis was from a separate microbe or was an effect of the flu?
As I recall, the article I read described victims as having subsequent mental problems and that description seemed to fit my father. I do know that, in spite of this ailment, he led a productive life from the early 1920s on into the 40s. I was pretty young but do recall that he continued to work after the war started and I believe that he had to stop working around 44.
He worked for the railroad as a station agent and telegrapher in my home town and was never unemployed, even during the great depression. Of course, I didn't come along until 1936 and I guess by then the worst part of the depression was over.
If you're interested in this, just try Googling "1918 flu epidemic" and see what you come up with.