Life duration of someone with congestive heart failure corrected by diet?

No way to know. Congestive heart failure has many, many causes. Without knowing the cause and severity of congestive heart failue, there is no way to answer this question.
Most likely no. Corrected would imply cured and even though diet (i.e.: low salt, vitamin supplements and weight loss) can help, congestive heart failure (CHF) usually means there is significant underlying disease of the heart muscle and a cure is elusive. The outlook for someone with CHF has a lot to do with what caused the heart problem in the first place & treatment will almost always include medication.

Related Questions

Names of most suitable ssri antidepressant needed for multiinfarct stroke dementia patient, 67, with minor congestive heart failure, atrial fibrillation, diabetes. Dosage and duration info appreciated.

SSRI. I'd start with an anti-depressant from the selective serotonin reuptake inhibitor group that have shown to be beneficial in cases of vascular dementia. Either zoloft (sertraline) (starting at 12.5 or 25 mg wth increase to 25 or 50 mg eventually and even higher doses) or Celexa starting at 10 mg and then increasing to 20-40 mg eventually may be a good start.
Not how it works. One does not get mental health treatment on the internet. This is not how medicine works. Treatment for these serious conditions must come from a physician who knows and is treating the patient. The health tap application clearly states that we cannot provide treatment advice.
SSRIs. There is some evidence that ssris help with post stroke remodeling where the brain works on regrowing connections between brain areas that were not killed by the stroke. There is also evidence they help prevent post stroke depression that is very common. Not much reason to think one ssri is better than another. See your prescriber for specific dosage recommendations.