The Redshift COPY command uses PIPE '|' as the default delimiter character. If your files are delimited by another character (comma in your case), all you need to do is add the DELIMITER keyword to your COPY command.
copy temp from 's3://bucket/top-1m.csv' credentials 'blah blah blah' delimiter as ',';
or for comma separated files:
copy temp from 's3://bucket/top-1m.csv' credentials 'blah blah blah' csv;