If I import my Forms Central forms into JotForms, does it affect the Forms Central Account?

First I would like to welcome you to JotForm.

Now in regards to your question - no it will not.

All our tool does is that it makes a copy of your data and forms in your AFC account and places it into your jotform account.

The process itself should not take long neither.

I would suggest taking a look at the following blog posts:

Import Both Your Forms and Responses in a Single Step from Adobe FormsCentral

JotForm vs Formscentral Comparison

7 Reasons Why JotForm is the Best Adobe FormsCentral Alternative

Of course if you have any questions or need our assistance, just let us know and we would be happy to assist.