PITR is the ability to restore a database cluster up to the present or to a specified point of time in the past with the help of WAL’s. PITR uses full database cluster backup and the write-ahead logs(i.e WAL’s). For that we should have cluster level (file system level) backup like pg_basebackup.
In PostgreSQL it is possible to have PITR but it requires file system level backup (like pg_basebackup).
So, It is not possible to do PITR with pg_dump backup.