Under these circumstances it's quite likely that your friend should already be represented by a court-appointed child welfare law lawyer. In Oregon child welfare law is called juvenile dependency. If he has a lawyer he needs to get in contact with him right away.
If your friend doesn't have a lawyer appointed to represent him yet he needs to get one appointed right away. To do so he first needs to know which county is hearing his child welfare case. Then he needs to contact that county's juvenile court to request the application paperwork for court-appointed counsel. Such requests are almost always granted and a parent is almost never required to reimburse the state for their public defender's fees. So if he doesn't have a lawyer he needs to get on that right away.
Alternatively his friends and family could retain a child welfare lawyer for him. Even though your friend is probably financially eligible for court-appointed counsel, there are some advantages to retained counsel, chief among them that the parent gets to choose his attorney rather than having the government randomly assign one to him.
There are many court-appointed child welfare lawyers (and case workers and judges) who are experienced, well-trained, passionate, competent, and so on. Those people tend to be the ones who could use their time doing more lucrative things but choose to practice child welfare law as public service. In other words they choose to suffer out of a sense of duty.
There are also a great number of court appointed attorneys, case workers, and even judges who are lazy, complacent, incompetent, ignorant of the law, uncaring, self-righteous, and unfortunately also jaw-droppingly stupid. These people tend to bully parents and children into doing what they think is best rather than what the law requires. Those also tend to be the people who are involved in this type of work not because they care or understand the high moral calling of this area of law, but simply because they're not qualified or trusted to do much else. These people tend not to take their respective roles in the system too seriously. They are often calloused and indifferent to parent's rights or children's desires for reunification.
So again, with a court appointed attorney it's luck of the draw. Sometimes you get great. Sometimes you get awful. Sometimes it's hard for a parent to be a good judge of their lawyer because even good public defenders have to choose which cases to prioritize. Also child welfare lawyers, even the great ones, are often spread too thin to expend a lot of energy reassuring their clients.
In any event, it's important that your friend get in touch with his lawyer and his caseworker. It is also important that he use his time in prison to make use of all available classes and resources. The Oregon Department of Corrections offers a good variety of services to include parenting classes but unfortunately due to budget cuts availability is limited.
Time is of the essence. Your friend's rights may already be subject to a termination of parental rights (TPR) petition. Under the Adoption and Safe Families Act (ASFA), the government has to find permanency for any child in substitute care (i.e. foster care) for more than 15 out of the past 22 months. So it's likely that the government has filed a TPR petition and that case is moving forward.
If your friend's lawyer is smart he or she will be aware of the recent caselaw suggesting that incarceration alone is not a basis for termination of parental rights. Rather the government must show that reunification of the family cannot occur within a reasonable amount of time as defined by the child's particularized needs. By the way, it's usually towards the end of a child welfare case that the government suddenly discovers that a child has special needs... so if you put two and two together you'll understand what they're doing there.
So wish your friend good luck. He'll need it.