They would become even closer. The shared responsibility of having a baby would strengthen their bond. Eddie would be more protective of Venom, and Venom would be more gentle towards Eddie, knowing they are in this together for the sake of their future child.
One possible plot could be that they face a lot of challenges in preparing for the baby. Maybe they have to find a way to keep the baby safe from Venom's enemies. They might also struggle with how to raise a half - human, half - symbiote child, like figuring out what kind of diet the baby would need.
Generally, Eddie Brock survives in the comics. However, there have been some complex and alternate storylines where his fate is less certain or temporarily in jeopardy.