It isn't possible to for an attorney to tell you whether or not you will win; that is for the court to decide. You should contact an attorney in the appropriate jurisdiction (it appears that is HI) and they can advise you as to whether or not you should move forward with a petition to terminate parental rights.
A Petition to Terminate Parental Rights is a petition to the family court asking the court to take away the rights of a parent by court order. It is always important to seek competent legal counsel before filing a Petition to Terminate Parental Rights. State laws generally require very specific information to be plead in a Petition before the court will even consider it.
The focus of inquiry in most jurisdictions is the best interests of the child as well as the conduct of the parent toward the child.
These considerations generally include:
The Child's wishes;
Abandonment of the child;
Neglect of the child;
Unfitness of the parent;
Failure of parental adjustment;
Risk of serious physical, mental or emotional injury to the child if he were returned to, or remains in, the home of his parent or parents;
Only token efforts by the parent or parents (a) to support or communicate with the child, (b) to prevent neglect of the child, (c) to avoid being an unfit parent, (d) to eliminate the risk of serious physical, mental or emotional injury to the child, or (g) with respect to termination of the parental rights of one parent, the abandonment by that parent.
Pleading to satisfy these considerations must be done with care. When considering these factors, the court's final decision will not only rely upon the plain language of state statutes, but also decades of complex and seemingly contradictory decisions from previous cases.
Again, your best bet is to consult with an attorney in the appropriate jurisdiction and they will be in the best position to advise you.