Boyfriend (M33) not keen on kids. How do I know if this is a deal breaker for him?

Ive gotten serious with this man pretty quickly (about 3 weeks in) and hes been really communicative about who he is which I really appreciate. We are compatible in both easy and hard topics so far. In the process of talking about what we want for our future, hes said he isnt keen on kids and thinks it would be hard to change his mind. My gut tells me to pump the brakes and to get to know him more. I want to be confident in knowing what it would be like to know we are both on the same page about kids. I am a childfree woman (33F) and I want to know what questions to ask or how much more to get to know him before deciding to see where this relationship goes. I really like him and this is the first time that I want to explore something long term. How do I know when its time to talk about it more or if I should start slowly backing away?<br><br>TL/DR a guy that Ive only recently gotten serious with is unsure if he wants kids. I am childfree. How do I know if he is worth getting to know more?