Explicitly stated where?
Also, early-game quotes about the Ascians' plans are shaky at best - for all the writers try to look like they planned things all along, I would say there has clearly been a shift in the Ascians' intended goals (if indeed the writers had a plan beyond "say ominous things about being close to it and we'll work out the details later") and they've done their best to smooth over the join, but the cracks still show.
Also, the fact that G'raha says nothing about Zodiark's reawakening having happened in the post-eighth-Calamity timeline makes it even less likely to be true. He's been working with a group that knows about Hydaelyn and Zodiark and has done research into the cause of the Calamity to the point of identifying the rejoined shard. I don't think Zodiark's awakening would escape their notice, and I don't think the writers would want to not mention it happening because it would be a great way to raise the stakes even higher. Even more so with the "hopeful epilogue" to the other timeline's story in Tales From the Shadows.