My father is just about recovering from a severe sepsis infection that included septic shock. still has low grade fever. how long does recovery take?

Sepsis: It can certainly depend on the etiology of the sepsis and the degree of organ dysfunction that occurred. Some recover fully, some take weeks, some never quite recover organ function and cardiac, pulmonary, brain and kidney function may be impaired afterwards. If he is still with fever days/weeks into therapy, i would make sure he has been evaluated for endocarditis with blood cultures and an echo.