Load gdb script from commandline:

gdb --command script.py


Automatially load gdb_python-script:
.gdbinit

source /path/to/hello.py
source /path/to/foobar.py
etc, etc

THE solution:
gnome-terminal -- "gdb -x gdb_python.py" && gnome-terminal -- "qemu-system-x86_64"