I don't think FFVI would have been quite as huge as VII.
Even if everyone agreed FFVII is inferior to FFVI (we don't all, I know), it doesn't guarantee the game would be more popular. I have a feeling there are other things FFVII has over VI - the "cool" factor (big sword!!1), the story is more personal (Cloud as the definite main character), the game's darker theme, the art by Nomura, etc.
That's my take on it, anyway.







