The only way to do it now is just by making exact copy of map, so you would have 2 maps. Make door at gate where player will go and set door to warp at second map. On second map, place player in position where's your second gate. If you still don't understand, try to play few experimental levels, there should be some example of it.
You can create a new robot spawn item and set it to trigger on a pickup event. Group it with a pink squid teleporter set to door mode. This only works one time though, after which the teleporter has been "picked up" and no longer exists and the spawn point has been already been triggered.