Retirement tax questions

It depends.

If this is his Canadian social security income, you will report the income in the same box that you report gross social security income from the US. 

If this is Canadian Registered Pension Income (RRSP or RRIF) TurboTax has entry screens by following this path in TurboTax:

1. Go to the Federal Income category.
2. Go to the Wages and Income subcategory.
3. Find the section labeled Retirement Plans and Social Security.
4. Click start or update on the line labeled Canadian Registered Pension Income.