We had a similar problem where a CSV file we get supplied either has 275 or 256 columns.

To resolve this we read in the first line of the CSV file and take the length of that line. We then replace the delimiters with nothing and take another count of the length. The difference is the number of delimters. Depending on that we branch out to one of two import steps within the SSIS package.

Hope this helps / points you in right direction

Screen shot attached.