So, this question depends on the severity of the Myiasis and how much deep tissue has been damaged, so I will give you a broad answer, that may help you and others in the future. Usually a bacterial infection spreads quicker than the rapid spread of the larvae, and bacterial infection can definitely kill an animal. If your vet has said he/she thinks treatment is the best option for your pup (versus being in too much pain, too much suffering, or too far gone thus suggesting euthanasia) then I would try my best to keep the faith in his educated opinion.
Since I don't have pictures, or am able to see a blood panel test, or blood/tissue culture to see what type of infection or bacteria is growing and how the body is reacting- I would suggest IF you are concerned enough you could always get a second opinion from another vet. Subcutaneous infections can get into the bloodstream, spread to the spine, brain, other organs etc. I have seen a dog go blind from Myiasis from the location of where the infestation and infection took place. I would take this seriously either way, no matter the severity, because even if "death" (as you asked) isn't the outcome, there could be other outcomes that affect your pup forever. I would try your vets treatment plan.
You did the right thing by taking him to the vet after topical solutions didn't work.