Coming from a Top 20 AUS CS:GO surfer, surfing is definitely possible on jailbreak.
I have only seen surf on surf_jail_wip and it is 100% possible to surf into the tube - though jump assist needs to be turned on.
The same argument can be said for jump_jurf, it is a jump map with surf ramps. If the air acceleration in surf was enabled in jump, it will not be consistent with the air acceleration people are used to on regular jump and other maps.