On peut en parler plus tard,

or, a stretch,

On peut en parler plus, plus tard,

would work. Your version, “plus en parler plus tard” seems wrong to me (native French).

étant donné que personne d’autre ne m’a encore demandé de venir l’aider.

I dropped the “pas”.

Also “personne” is singular in French. In English the absence of potential things is plural (there is no cars), but in French if there’s none, there definitely isn’t many. To me, it’s more natural. 🙂

If we start from your English sentence:

We can discuss it more later, since nobody has asked me to help them yet.

In the second part, we have nobody coupled with them, in French personne and some unknown pronoun…

Let’s see some simpler sentences:

• Personne ne l’a su → Nobody learnt about it
• Personne ne l’a vu → Nobody saw him/her/it _{(eventually them when uncertain of the gender)}
• Personne ne les as vu → Nobody saw them

If we now wonder how many people would get help, if help was requested, it would likely be one at a time for individual work, or likely a team at a time (i.e. many people) for team work. French would lean towards singular in the first case, and plural in the second:

• …personne ne m’a encore demandé de l’aider → people come seek help one by one
• …personne ne m’a encore demandé de les aider → groups of people come to seek help together

The latter could be reworded with aucune équipe instead of personne, but then more questions and more answers arise with the collective noun (discussed in more details here):

• …aucune équipe ne m’a encore demandé de l’aider/les aider

However, and just as a side-note, I would not word the sentence like this, though it might be a strictly personal point of view. In speech, and among many many variations, I would probably choose something close to:

• On pourra en reparler plus tard, puisque personne [n’]est encore venu demander de l’aide.