I would argue that you should capitalize 'Em when it appears in the middle of a title.
Style / Language / English: "Capitalize contractions and slang consistent with the rules above to the extent that such clearly apply. For example, do not capitalize o’ for “of”, ‘n’ or n’ for “and”. "
Example Case: https://musicbrainz.org/recording/62d6d79c-87fa-48e4-baa2-3c22f6271065/edits
“Gang Starr feat. Krumb Snatcha - Make 'em Pay” vs “Gang Starr feat. Krumb Snatcha - Make 'Em Pay”
I would argue that Make 'Em Pay should be the correct form. Anyone care to share their opinion.