I'd like to believe it's true but it just doesn't match up.

The most solid evidence being yeah, Cid's rocket being supposedly the first rocket that would go into space. That's quite an integral part of VII because every main character in the game has their own reason and their own story about why they hate the Shinra. So you can't just shrug it off, really.

I liken it to the IX reference to Cloud. 'i knew a guy with spikey hair who used a sword like this' or whatever he said. How could Zidane of actually known Cloud, did he travel to another world? Another dimension? Back/forward in time?

It's just a playful kind of nod, but I don't think in regards to the story it has any truth to it.