It's certainly impossible to answer in a single broad stroke for everyone, but that doesn't mean it's not useful or relevant to think about.

Chaos theory will very soon screw you in that endeavour. You generally can't make spredictions like that on a single life, since you'd have to perfectly simulate that life beforehand. I think that means it's a very useless question.

If that's so, then we're talking past one another. My point is that in my ethical framework, having a child is wrong. They are incapable of consenting as you point out, which is part of why I view it as wrong.

someone (idk if it was you, too lazy to look it up) asked "who [gave] someone the right". I said that rights aren't given.

Why?

... the principle of ontology, I'm guessing? There isn't a something to give consent, ergo it can't give consent.

The child surely exists before, during, and after its birth. Can't it be that the unborn human is incapable of consent rather than creating a paradox?

These binary cathegories of existence break down at the edges anyways. At some point it's mainly a process, at a later point, it's an entity. Ontology's a bitch like that.

I understand the chicken-and-egg problem you are describing, but I think it's incomplete. As a fully functioning human being now, if I look back at my birth, did I consent? Did I exist yet? I think I can say simply, "No, I did not consent to being born." Whether you ascribe a negative, positive, or neutral value to this is up to you. In my opinion, it's immoral.

Consent doesn't work like that. It can only be revoked at the moment. If something happens to you without your consent and you didn't know at the time, the best you can do is realize later that you didn't give consent. Something coming into existence can't give consent, since i, needs to exist, in order to be capable of consenting.

What do you mean "you didn't consent"? Would you have revoked consent, given the chance now, or are you lamenting that you couldn't give consent before existing?

Yes, however isn't this logic used to argue against abortion? I'd argue that a person becomes a full "person" at birth, which is perhaps arbitrary, but we have to define that point somewhere. Regardless of when we say a person "exists", they still cannot consent regardless.

Look at it in a more abstract manner. First, there are entities A and B which start a process P. This process results in entity C. Entity C would have to give consent to P, before it is an entity. But only entities can give consent. If starting P breaks consent, prematurely ending it sure as shit does (plz note, that I'm pro-choice; demanding consent of a non-entity is stupid).

That all said, is anti-natalism completely correct for everyone? I don't know. I'm sure our species going extinct would create lots of suffering for the dwindling population. Maybe on average, humans do not regret their existence. Does that mean it's moral to make more conscious beings who are capable of feeling that regret?

Remember that not everyone is a strict utilitarian.