Honestly, I'm in the camp of skepticism. It would be great if he would release his medical records surrounding this to prove what he claims vs what the doctors have told him. HIPAA would prevent the medical center verifying or denying his claims, even if Beck is or is not telling the facts of the situation.
I grew up with people who often claimed healing and clean bills of health after a terrible diagnosis only to be further inflicted or dying from the originally diagnosed disease. Or they exaggerated the original diagnosis.
And I'm certainly not implying miracles can't happen. Beck just always makes me suspect about his.