Initially it was used in RPs and forums by 12-year-olds that can't spell "doggy", meaning "doge" was pronounced "Dog-E". However, as its usage spread, people mocked it by pronouncing it "Doh-j". Doge wasn't really associated with anything until supershibe started blowing up and it was inevitably tagged as "doge". From there, there have been plenty of pronunciations as the general population has caught on, however the main one seems to be "Doh-j". Though, to answer your initial question, technically both "Dog-E" and "Doh-j" are correct.