The answer is that it depends. The fact that he takes medication is positive and very encouraging. It seems that he is aware that he has the illness and is willing to be treated for it. I point this out because at least half of people with schizophrenia do not know they have the illness and therefore refuse treatment for it. Their refusal to accept treatment decreases their chances of ever gaining control over the disease. But luckily, this does not sound like the situation you are dealing with.
Part of the disease of schizophrenia is the inability to communicate well or interact with individuals in a normal way. Some have described these traits as autistic in nature. These communication abilities vary among individuals with schizophrenia and some individuals have more trouble than others.
If your ex is willing to help you raise the baby and you want him to be a part of the child’s life, I think you should do what you feel most comfortable with. Remember that it is his child too. If you want him to be a part of the child’s life but are unsure about how he will act with the baby, let him see the baby but supervise his visits. It is difficult to know just how he will be around a child since I know almost nothing about him. You will have to judge this for yourself after seeing him interact with the baby. If you are concerned about dangerousness, know that people with schizophrenia are usually no more dangerous than people without schizophrenia as long as they are taking their medications, not actively psychotic, and not using drugs or alcohol. If you are concerned about his parenting abilities, maybe you can suggest, with compassion and understanding, that he take a parenting course. Perhaps the two of you could go together. I would also suggest that you try and learn about the disease of schizophrenia. This may help you better understand what your ex is going through and give you insights into how you can better interact and communicate with him. These are just a few suggestions. Ultimately, you will have to decide how much access he has to the new baby; a determination you may most accurately make after seeing how he interacts with the baby. I hope this helps.