I think the article is talking about the entire bear population eating 40k each day.
Seems to imply up to 40k/bear, but doesn't give much more for details.
It mentions moths are about a half a calorie each, so just from the moths a bear can consume 20,000 calories/day.
Sorry for being cheeky but the parent literally just addressed your question.
"It is estimated that an ambitious bear may consume in excess of 10,000 moths per day, with some estimates ranging as high as 40,000 moths per day."
"One group of scientists analyzed bear scat and revealed that a foraging grizzly could gobble 40,000 moths in a day."
Neither figure seems particularly compelling here, of its "eaten by bears" it seems way too small if it's "eaten by a [single] bear" it seems too big.