What are my chances of getting herpes simplex 1 from oral from someone who hasn't ever had an outbreak, but does have it? he got tested

Small but not zero: He probably has a positive antibody test, which means he's been exposed to the virus, but does not necessarily mean he has active hsv. The risk of such people transmitting the virus is small, but not zero, and can be lowered further if he takes an antiviral (valtrex, famvir) regularly. Whether long-term antiviral treatment is advisable must be decided by his doctor.