Ali Khamenei regularly talked about his favorite western books, Les Misérables, The Grapes of Wrath and Uncle Tom's cabin.
He told tactical thinkers in the Iranian regime to read Uncle Tom's cabin in particular to fully grasp how evil the US is.
When Khamenei said "this book [Uncle tom's cabin] still lives"... I don't think he meant that figuratily.
From all oh Khamenei's statements on Black Americans he clearly means it literally.