Yes, but how it affects it depends ... if he consolidates and keeps on top of his finances from that point forward, it will help. If he consolidates and things get further out of hand it will hurt it if he cannot stay current with his bills.
Credit card companies tend to have the worst affecton your credit - as soon as you miss a payment, they report it and your credit rating goes down.
Debt consolidation itself does not dramatically affect your credit score. However, the main issue with debt consolidation is that over 70% of consumers who consolidate their debts grow it back to the same level or higher according to(http://www.bankrate.com).
1. When you consolidate your debts, you are not learning how to manage your money better, you are performing a quick fixes, and quick fixes breakdown as fast as you put them together
2. You must take the necessary steps to learn how to manage your money by putting together a realistic budget
3. Create a simple to execute and even simpler to manage debt elimination plan
4. Make permanent decisions to change your spending patterns to spend cash for your purchases
Hope that helps