What are the chances of getting pregnant 6 years after tubes tied?

Unlikely: Very unlikely since it has work for so many years.

Depends: Depends upon several factors: your age and sperm count on partner being the most important. Most studies suggest women over 37 with tubal ligation do best with ivf instead of tubal reversal surgery. Remember that normal fertility at 39 is about 5-10% per cycle and after tubal reversal that is the best monthly preg rate you would have. Ivf is probably higher at 20-30% per cycle depending on testing.