If you're a lot bigger and stronger than someone, it doesn't matter if their gag reflex is intense. In fact, if you have a taste for the finer things, an intense gag reflex is preferable.
Consider the physiological reality of a gag reflex. The back of the mouth or soft palate is touched. The throat closes to prevent swallowing, while the larynx pushes upwards to expel any hazards. The abdomen contracts and the stomach spasms. Eyes water, saliva production ramps up. You can learn this in any textbook. But there's so much more you won't learn — a Platonic-Christian hatred of the body has always poisoned the integrity of our researchers.
They never mention how the cunt tightens up around whatever is inside it, or how much wetter it gets after they’ve been brought to the edge of throwing up once or twice. They don't talk about how tightly the asshole clenches, holds, grips you, how it won't let you move for a few moments if you gag them hard enough. There aren't academic papers dedicated to how good the throat feels when it wants your cock or your fingers out of it, on how sweet the thrill is of knowing your prey's neck and back muscles aren't strong enough to overcome the pressure from your hand on the back of their head.
They never mention how the entire body tries to get away at first, but if you overpower your victim, if you keep them where they are and keep fucking their throat with your fingers, they eventually just stop moving. They give in. They still gag and choke and cry, but their body learns escape is impossible. They go limp like a little bunny, playing dead.
Whenever a "masochist" brags to me that they have a weak or non-existent gag reflex, I lose interest. A true masochist understands that what is needed isn't easy compliance, nor even willing submission, but a total subordination of interests, the subsumption of one body under the will of another. My promise: if your gag reflex is weak, I will deliberately make it stronger.
Don't worry, it won't help you.