deceze is right, that is ISO8859-1 (AKA Latin-1) encoded text. Try this:
file_contents = CSV.read("csvfile.csv", col_sep: "$", encoding: "ISO8859-1")
And if that doesn’t work, you can use Iconv to fix up the individual strings with something like this:
require 'iconv'
utf8_string = Iconv.iconv('utf-8', 'iso8859-1', latin1_string).first
If latin1_string is "Non sp\xE9cifi\xE9", then utf8_string will be "Non spécifié". Also, Iconv.iconv can unmangle whole arrays at a time:
utf8_strings = Iconv.iconv('utf-8', 'iso8859-1', *latin1_strings)
With newer Rubies, you can do things like this:
utf8_string = latin1_string.force_encoding('iso-8859-1').encode('utf-8')
where latin1_string thinks it is in ASCII-8BIT but is really in ISO-8859-1.