There is no evidence he would have survived had he been hospitalized three days earlier. There is no specific treatment, care is supportive.
Actually, there may be a specific treatment that can be highly supportive. When I first heard about Ebola it sounded to me like runaway scurvy. I Googled “Vitamin C in treatment of Ebola, and there found a number of articles supporting the idea of using very high doses of C to treat Ebola. Apparently one of the first things Ebola does is totally wipe out any reserves of C in the body. Also look at Dr. Frederick Klenner, a doctor who pioneered high Vitamin C therapy for a number of toxic conditions and viruses.
Some supportive treatment would have saved his kidneys and liver. Drugs/Survivor Serum given earlier would seem to have helped....
It would have been of great benefit to the community if he had been immediately hospitalised, and therefore isolated. I am amazed that he was seen and let go home.
There is a Liberian doctor, Gorbee Logan, who has been treating Ebola patients with lamivudine, an off-patent antiviral normally used to treat HIV and hepatitis-B cases. Dr. Logan claims to be 13 for 15, the two losses being the ones who were put on the drug the latest.
Common sense indicates starting treatment three days earlier might have made a difference.