The entity feeds off of the emotions of both killers and survivors, it especially fixates on the feeling of hope.
The Entity does not feed upon what we would call "food", as it's lovecraftian entity similar to the old ones of Bloodborne. It requires no sustenance, other than the emotions of others. One it seems to get the most out of is Hope. The killer's job is to force a survivor to hope for escape, and the entity sucks it out of them with each sacrifice. Eventually the survivors will break, either into oblivion, the escape they've wanted, or become a new killer in turn.
And so, the cycle will begin anew, with new survivors in their stead. Since this is timeless, then there is no end to it.
The entity is growing with strength, allowing it to create more complex and brutal killers, even adding monsters it's roster...
...all for the hope of the campfire.
I should be working on my study guide but instead here ya go.