I'm not sure if you're being serious, but I disagree if you are. Any drug can be the gateway for a person at risk for addiction. I don't have hard data (and I suspect there is none proving weed is the gateway drug, but am happy to be educated) but my guess is that alcohol is the gateway drug for a vast majority of Americans.
Can weed be a person's gateway to harder drugs? Sure. Is it the gateway drug? I don't think so.
Can weed be a person's gateway to harder drugs? Sure. Is it the gateway drug? I don't think so.