Hi Todd,
There is no way to check how many columns are there in the CSV file through Import CSV Data using LOAD LOCAL as it simply executes a data manipulation statement “LOAD DATA INFILE” to import.
For you case, you can import CSV File through Import External Data wizard. Through Import External Data –> Column Mapping Section you can check which fields you want to import from CSV and the target table. Also, in Advanced Options select “Import into existing” option. Please see the screenshots and you can also go through program's help menu.
Thanks & Regards,
Khushboo