Dear @Oajele,
Welcome to the Wefugees Community and thank you for your question. Just to mention it, we are not lawyers at this platform and information we provide here cannot replace individual legal advice.
The permanent settlement permit for students and the one for family members of Germans are subject to different requirements.
As far as I know, for the latter, you must have held a corresponding temporary residence permit (according to section 28 of the German Residence Act as father of a German child) for at least three years. You can check this list of requirements as an example for people living in Berlin.
If I understand correctly, you are still holding a residence permit according to section 16b as a student, right? If you not change your type of temporary residence permit, successfully completed a university degree in Germany and subsequently hold a residence permit as a skilled worker or researcher, you can apply for a permanent residence permit after 2 years of having a residence permit as a skilled worker or researcher (independent from your family status). Furthermore, you are required to have contributed to the pension insurance for 24 months. You must have a job and speak German at level B1 to apply. For more information on the general requirements, please see Handbook Germany as well.
I hope this helps and please don't hesitate to get back to us with any further questions.
All the best,
Meike