I can't say for the peanut butter cups but I did have one of the Russle Stover Toffee squares tonight.
The package info is:
Total Carbs: 15.8g
Fiber: 0.8g
Sugar Alcohols: 14.6g
Net Effective Carbs: 0.4g for two pieces.

Hope that helps even if it's a different candy, it should give you a pretty good idea.