Near as I can tell, he lived from 1911-1975, so he was 64 when he died.
Pretty young -- according to his biography: "He died of a heart attack - probably a result of cardiovascular disease. In Euell's day it was not unusual to smoke cigarettes or to add high amounts of saturated fat (bacon grease, butter, egg yolks) to his wild foods. These risk factors combined with his hard life and lack of exercise in his later years (arthritis pain limited his movement) undoubtedly contributed to his death.
"
Id say being 65 greatly contributed to his death