If the user extracting is a “ordinary” user, the files will be owned by that user (by default).
If the user extracting is a super user, then the files ownership will be preserved (by default).

Note: This is by default and can be overridden when needed:

From the manual page of tar:

--same-owner
       try extracting files with the same ownership as exists in the archive (default for superuser)
 
--no-same-owner
       extract files as yourself (default for ordinary users)