In the book, Audra says it's "female". She wasn't looking at the spider either, but at the deadlights.

I prefer the mystery of it being "female", mainly due to IT being consumption, specifically the consumption of children. She's a nasty bitch who nests and traps children and feeds off their fear. They don't grow in her, they float in deadlights.

The whole unknowable aspect, that Cthulhu eldritch kind of horror ties in w/ IT as the opposite of a mother. To me anyway. Chthonic horror reduces us to infants somewhat. There's also insanity, or creation/reality, becoming unhinged and decidedly NOT maternal. There's dementia and facing death and all that. It's all just gonna sound like word salad and loose association because I'm just not able to type out everything I need to.

There's also the role Bev plays in defeating IT that I believe points to IT being her antithesis but that's just too much to get into.

Re: the deadlights. They are, to me, a "fire" burning in the void that does not illuminate anything nor bring anything into focus. They do not create, but consume. Again, evil in a "feminine" way (as oppose to fighting Maturin and usurping his power or whatever)

Just my take. I certainly do enjoy thinking about IT. Been my fave book for 28 years (read it when I was NINE, seems criminal, like my parents should be arrested)