That sentence misses the very definition of philosophy and its purpose. It is true that Ayn Rand never had children and didn't talk much about parenting (although she did in various Q&A and also spoke about education - was very fond of Montessori for example), but that doesn't mean that Objectivism, which is Ayn Rand's philosophy, has no value to a parent or child.
Ayn Rand offered Objectivism as a philosophy for an individual human being, to aid in living in the natural world as a human. It is a comprehensive world view that speaks to the nature of reality, the nature of human beings, our relationship to reality as well as ethics, politics and aesthetics.
An individual's choice to raise children is personal and individual and Objectivism would argue that it is a moral choice to become a parent if you value raising children of your own, can afford to do so and are willing to accept the enormous life-long commitment and responsibility that doing so entails. A child's relationship to their parents, what rights children have and what a parent's responsibility is to their children are all things that Ayn Rand actually did speak about during her life, but the one thing I will grant you is that the fictional characters in her books were mostly childless and that probably had a lot to do with the fact that she herself was childless and so it wasn't something she felt moved to really talk about through her writings.
As for "need to raise them if you want a society to continue,"...
Objectivism certainly has a lot to say about an individual's relationship to "society", the very definition of "society" (an abstract concept referring broadly to a group of individuals) and it rejected the philosophical notion of "duty", not to be confused with "responsibility." Individuals have responsibilities, which they accept willingly. A parent, for example, has a responsibility to their children. Pet owners have responsibilities to their pets. People enter into contracts and relationships, make promises to one another and agree to work together collaboratively. All speaking to responsibilities. A duty, on the other hand, refers to an obligation imposed at birth to which someone has no ability to opt out. The duty to have children, for example. "If you want society a continue..." Objectivists would say "If you want children and a family and are prepared to accept the responsibility then do it for yourself. But don't take such a major life decision lightly, and you don't have a 'duty' to do so."
