The verse is actually there in the ChAndogya Upanishad (CU).
CU 3.6.1 states:
Tad yat prathamamritam tad vasava upajivantyAgninA mukhena |
vai deva asnanti na pivantyeadevAmritam drishtvA tripyanti ||
Among them, which is the first Amrita, keeping Agni in front, is
enjoyed by the Vasus. [But, in the real sense], the gods neither do
eat nor drink; they are satisfied upon seeing (drishtvA tripyanti) the Amrita only.
And, the highlighted half verse repeats itself in 3.7.1, 3.8.1, 3.9.1 as well as in 3.10.1.
Now, does that imply that gods actually do not eat/drink and can enjoy the food by seeing it only?
Because this is refuted in Aitareyopanishad (AU) 1.3.
It is stated that when Iswara created food (or Anna) first, he tried to eat it/accept it by various sense organs, but he was not successful.
AU 1.3.4 states:
First he tried to accept the food with sense of smell but did not
succeed. If he had succeeded everyone else (thereafter) could have
done the same (i.e could have enjoyed the food by smelling it only)..
And, then, in AU 1.3.5 it is said that he then tried to accept the food by vision.
He then tried to accept/enjoy the food using eyes (vision) but without
success. Had he been successful then, everyone else would have been
able to enjoy food by seeing it only thereafter..
Eventually, he succeeded with the help of the Apana Vayu. And, that is why we have to eat to enjoy the food.
So, the possibility of food intake (or enjoying the food) by simply seeing it is ruled out here.