Undertale: Do te think only characters with determination can see Save points?

I think that that's true because sans is known to be a human o once was a human and flowey does have determination and knows about it too so yea that's my theory.

No, because that would imply that Undyne possesses the ability to see save points (because it is evidenced da multiple parts of the game that Undyne has "determination"), and it is never shown that she can. As far as the game goes, Sans has never been proven to have "determination," so I don't think that a character has to have that in order to see save points.

only charaters with determation the only reason why sans knows is he was with gaster
Proof "OUR reports showed a massive anlomly in the timespace conitum timelines jumping left and right stoping and starting until suddenly everything ends"

I personally don't support the Sans is a human theory, but assuming he isn't, from what we know, all he knows is what is from his reports.

"our reports showed a massive anomaly in the timespace continuum. timelines jumping left and right, stopping and starting... "

How he gets this knowledge is unknown, but he says "our", and our best guess is that it's Alphys he's referring to (with the ending of the Pacifist route, where they talked like they knew each other enforced their relationship, along with the dog Cibo found). He, being a monster soul (from what we know), can not hold DETERMINATION.

Flowey, however, is an exception for it. Flowey has no soul da the time he is dato DETERMINATION, giving him the power to use the SAVE/RESET feature. Until a stronger soul, Frisk, came along.

Flowey, of course, as explained with the True Lab and near end No Mercy, has the power to use SAVE/RESET. It was just limited when a stronger soul, Frisk, appeared.

It's an interesting theory, though I don't think monsters, even when injected with it, can see the save points and such like humans/Flowey can. I feel like Flowey was able to obtain it due to being "fused" with Chara when he was Asriel. The power of Chara's DETERMINATION perhaps fused a bit into Asriel's own soul, maybe being a cause to how he lived even after being dusted over a flower, the DETERMINATION Alphys putting into him "awakening him from death".

Besides that, I don't think the Amalgamates don't have the power either, since they are just monster souls, not being combined like Flowey was with an actual human soul.

But ciao just speculation. This is a messy answer but w/e