This depends entirely on the options offered by the copyright holder.
Adding a publication to a repository is a form of disclosure and reproduction, which only the rightsholder is allowed to do. Much will depend on the terms and conditions of use the copyright holder offers to the actual author(s) or on the publication's licensing terms and conditions.
For authors and co-authors at research universities, the Taverne amendment means that if the work is partially financed by government funds, it may be made publicly available after 6 months, for instance in the institution's repository.