Through extensive research, as far as the Demiplane is concerned, the ability to determine its time is either DM decision or create an epic Genesis spell in which it functions the exact same as Genesis but with more clarification it's abilities.
However, if including third party material, specifically the book Chronomancy: The power of time, A chronomancer, having physically seen time, would be able to visualize time as an environment and thus able to speed up time in a created Demiplane when executing the Genesis spell.
As far as the gate part is concerned. That is actually raw.
In Dragon Magazine Guide #221 Article 101 uses of portable hole we see that:
42) Set up a permanent gateway to another plane inside the hole.
So that answers that question.
Permanent access to a permanent gate to a Demiplane that may or may not have the flowing time trait.
Not to mention a very handy getaway location as it's already stated that a portable hole can be picked up from the inside.
From the item details:
This hole can be picked up from inside or out by simply taking hold of the edges of the cloth and folding it up. Either way, the entrance disappears, but anything inside the hole remains.