In most bankruptcy cases you will pay back nothing to your creditors. In other cases you will pay back what you can afford.
Debt negotiation typically works by you making a payment to a company and then those companies asking your creditor to accept a payment of less than you own them. Debt negotiators typically charge high fees for their services and often times the monthly payment is SO high that you cannot afford more than a few months of payments.
Most bankruptcy cases do not require any payments to creditors and typical legal fees and expenses are usually about the same as 3 or 4 months worth of payments to the debt negotiator instead of 3 or 5 years.
Some people will need to file a chapter 13 bankruptcy and pay back a small percentage of what they owe. In this case you only pay what you can afford and not what the credit card company wants.
I encourage you to take advantage of the free bankruptcy consolation and learn more about bankruptcy and debt negation.