Isn't Setsuna's combat system pretty clearly a riff on Chrono Trigger's combat system?
Oh yeah, it's a direct copy, but in pretty much every other sense I think it's a swing and a miss on the CT comparison front. Even combat, direct rip as it is, isn't anywhere near as good feeling. Lost Sphear is a better second attempt, though it's still a ways off. My point is really more to say: it doesn't really matter what a dev (or anyone else) says the influence is, it's what's there that matters. It can be a useful shortcut to help someone understand if you'd like a game, though.
Mind you, Setsuna is a thousand times more like CT than Octopath is like FF6. Which brings me to...
Well, we do care because it tells you what they tried to achieve when creating the game. Author's vision is like the most important thing to take in account when analysing something. In his writting, Jason does not take it into account. He just says "other reviewers compare this game to FFVI, fuck them, I compare it to SaGa, there is like 0 interactions between characters !!". He doesn't talk about producer's vision of it being a successor to FFVI because he hasn't said it when Jason wrote his article. So, when someone said "ok Jason, you said other reviewers were dumb fuck... but now even some of the authors of the game says those guys were right. Can you elaborate please ?" He just come and say "lol". Game critic said it is, so it is.
Whatever Jason's response was and whatever you make of its tone, after like 25 hours with the game I don't know what to tell you other than whatever their intent was, it doesn't really resemble FF6. To my eyes the battle system - completely different, closer to FFX if you really want an FF comparison. Progression - see previous. Story - delivered in a completely different way and with a very different style/tone. The area where it skirts closest is in visual identity - the design of the world and the art style that delivers that definitely evokes that look - but even then it's still pretty far from it, I think, just due to how the game uses things like character animation on the field etc etc.
Mind you, I don't know why this is something everybody's getting hung up on: the game is still really fun and interesting imo (something Jason might not agree with, but that's how opinions work) - though some of the areas where it is interesting don't quite work... but the embargo really prevents me from getting into the nitty gritty of that. It's still worthy of your attention regardless.
Like, a colleague of mine asked me on twitter earlier today if he should definitely pick up Octopath given that FF6 is his favorite game of all time. My answer was just - wait for the embargo and read some reviews and get a real good idea of what the game is in-depth, as the 'it's like FF6' shortcut isn't actually a very helpful or accurate description, regardless of what the developers say. The fact my answer wasn't an immediate yes should speak to where it stands compared to FF6 in terms of similarities. I think it's gonna be a good thing in its own right, tho.