As I understand it, there are limited ways to treat it. Medication, ablation ( or a more invasive surgery), or live with it. I am now, after 10 years at the point where I am ready to have an ablation. They really are very safe and quality of life is important. I think you have to get down to the point where ablation seems the lesser of 2 evils. Good luck to you -- keep us posted.
A heart ablation may be the best approach to a cure, but it has to first be established that he has a good chance of the procedure working - the answer to your main question. This isn't just his decision, he has first to find a doctor who believes it has a good chance of working. Then nothing is guaranteed for life, but it is least invasive procedure that can effect a cure.
Has he ever had an electrocardioversion? The first approach in my experience is to try drugs - seems that has been tried and doesn't work, next on tries a electrocardioversion (electric shock, done in a hospital) followed up with medication to hold the heart in normal rhythm. The next step would be to consider an ablation.
I, and others, manage to live with AFib using the "rate control" approach. The doctors have given up on trying to effect a cure, even a temporary one. Instead I take beta blockers and calcium channel blockers (both low cost generic drugs) to keep my heart rate at a reasonable level, for me that is a HR below 80 BPM at rest. A resting HR below 100 is considered acceptable.
I also take, and I hope your husband is too, and anti coagulant (warfarin in my case) to prevent formation fo blood clots and a possibility of a stroke, one of the risks one faces when they suffer from AFib.