Is there any reason you think it could not?
Yes, they can use it.
Once you make a statement it becomes part of the evidence. You cannot remove evidence from vision.
They do not usually caution witnesses. They are not in a cautionable position.
Generally speaking anything they say will not be taken down and used as evidence against them.
If this is a S9 statement then it can be used.
Sorry if that is bad news.
Can I clarify anything for you?