In general slumping will not remove the evidence of etching. There will be very little effect on etching on the bottom even at fire polishing temperatures.
When the etching is on the top side exposed to the radiant heat of the elements, you need to be careful to use the lowest practical temperature for slumping. It is possible to achieve a satin finish to a sandblasted surface at 677ºC with a soak of two hours. It depends on the delicacy of the etching texture as to whether the slumping will affect it much.
The more the glass will need to move during slumping the more distortion will be apparent in the finished piece. This can be minimised by using a low heat for considerable time.
If the mould is very detailed, it would indicate that etching should be done before the slumping due to difficulty in attaching the resist to the shaped glass, unless you paint it on. But again, a significantly long soak will be required to achieve the detail of the mould.
If it is a simple and relatively shallow slump it may be easy to etch after shaping. It is a question of how easy it is to get the resist to conform to the curve.