I haven\'t been able to get ffmpeg\'s drawtext video filter to draw apostrophes/single quotes when they are in drawtext\'s \"text=\" parameter, even when I escape them. Doub
Special character escapes are like violence: if they're not solving your problem, you're not using enough.
ffmpeg -i test.mpg -vf drawtext=text="It\\\\\'s so easy"
Produces a textual overlay that includes an apostrophe. The text is being parsed a couple times, so you not only have to escape the quote, you also have to escape the slash escaping the quote. Twice.
Your alternative of using a textfile might be a better method in this situation.