Well, I guess it must be something proportional to the original filename plus the new filename for symlinks, and only the new filename for hardlinks, but how does this affect the disk space exactly? I just made a folder with about a hundred thousand symbolic links in it, and the folder still reported 0 bytes usage. I even think the free capacity of the drive remained the same. Then I permanently deleted the folder and the sizes still stayed the same.
Could I fill up a hard disk just with symlinks? Or does NTFS have a limitation that no more than X symlinks are allowed on one drive/in one folder, so the capacity of the drive cannot be reached?