The argument assumes that the potential for positive impact justifies the risk of suffering. While it's true that people can positively impact others, the notion that we should create lives solely for the benefit of others fails to consider the suffering the individual might endure. It also disregards the possibility that the person may not have any significant positive impact on others, or that the positive impact might be minimal in the grand scheme of life. The premise that the absence of someone leads to a "worse life" for others is subjective—there's no universal evidence that not being born is a "net negative" in the context of a person's contribution to others' happiness.
This argument relies on a generalization that the average person's life is balanced more positively than negatively. While it's true that most people experience moments of happiness, it's also true that suffering, pain, and hardships are ubiquitous parts of life. Many people experience prolonged periods of suffering, mental health struggles, or existential challenges that overshadow their positive experiences. Assuming that the positives will always outweigh the negatives ignores the reality that for some, the suffering can be overwhelming and life-altering. Also, different people's capacity for positive experiences and resilience varies greatly, meaning the "net positive" claim is not universally applicable.
You're right that we don't have definitive evidence of what happens after death. However, the statement that "death equals no suffering" is based on the premise that death is an absence of experience—it's not necessarily claiming that something specific happens after death. It's more about the idea that, if death is truly an absence of experience (as many atheists and materialists believe), then there would be no suffering in that state. Whether or not there is something else after death is speculative, but if we accept the idea of death as the end of consciousness, it can be viewed as a cessation of suffering.
This statement is highly speculative and relies on an unfounded assumption that we might have been suffering before birth or that we could be subject to eternal torment after death. The concept of being "freed" from suffering by being born into existence is an untestable assumption. Additionally, it presents an extreme and unverifiable scenario (burning in pits of lava) to counter the idea of death as a cessation of suffering. The reality is that we simply don't know what happens after death, and it's not reasonable to use unfounded hypothetical scenarios as the basis for making conclusions about the morality of bringing new lives into the world.
This is true to an extent—questions about the afterlife, the nature of consciousness, and the morality of bringing new lives into the world are based on personal belief systems, interpretations of evidence, and philosophical reasoning. However, the fact that we cannot prove something one way or another does not mean we should disregard it entirely. It means that, in the absence of definitive evidence, we must base our beliefs on the best available reasoning, while also acknowledging the limitations of our knowledge. In the case of antinatalism, the argument is based on the known realities of suffering and the potential for harm, rather than speculative assumptions about the afterlife or pre-existence.
In conclusion,your statement relies on a mixture of assumptions, generalizations, and speculative scenarios that aren't necessarily grounded in evidence. It also doesn't sufficiently address the ethical considerations surrounding the suffering that individuals may experience during their lives, and whether that justifies bringing new lives into the world.