You don't get to claim the entirety of the green revolution here, and most of those 1 billion would not have been born in the first place if the Harber-Bosch process did not exist. If we are going to go to that particular level of sophistry then I would add the four generations of descendants from WWI deaths and three generations of WWII/Stalin-induced famines/Great Leap forward deaths, etc. Playing alternate history speculation is interesting, but trying to project any particular distance beyond the immediate point in question is a fools errand.
No, 1 billion already-alive humans would have starved to death if not for the green revolution. Malnutrition plays a role in over half of all deaths today. It was even more commonplace before fertilizers and high-yield crop strains.
