If I understood your email correctly the SEVIS system has no connections with H-1B status meaning SEVIS is only for F-1 and J-1 visa categories. The change of status to H-1B will not be reflected in SEVIS. The SEVIS will automatically terminate your status after the 60 days grace period of your I-20 or your inernational officer will have to manually end your program. Since you have your new I-94 as of 10/1 your status will be H-1B from that date.