Not a good idea in our opinion, we don't have much experience with frogs and toads yet but we are working with gecko's for years.
The toad will most likely need a water source, the gecko might drink it and get slowly contaminated by the toad's poison.
Also golden gecko's ( Gekko badenii ) aren't the most docile of all gecko species, they are most likely gonna attack the firebelly's.., if it's not a big deal and you have the room, housing them seperate is the way to go.

Greetings.