No Win 8.1 will either format and install new or Delete most of Win7, you will have Personally stuff left and any programs you had in a Old Windows folder but it won't be bootable. There are ways to make it a Dual boot but that's requires 3rd party software like Linux Grub.
On a personally not Win 8.X sucks unless your running a touch interface, even the lobotimized desktop annoys me. The only reason I would recommend the upgrade would be to get the free copy of Win 10 when it comes out for Win 8 users.