It depends. YouTube can only pay out royalties if a video has been claimed by an advertisement and therefore monetized. If a video has not been monetized before, there will be no retroactive royalties to pay out.
If, perhaps, the sound recording owner has been claiming a video and no one was claiming the composition, we would receive an adjustment payment for royalties earned previously when we then claim the video.
There are other situations that can affect whether we can collect retroactively on YouTube, including whether there were other content owners previously or if there is conflicting ownership. If you have a question about a specific video, feel free to send us the link using the chat box on the bottom right hand side of your account.