The only thing from that I can guarantee is:
If OLEDs come in 64 and 256 (regardless of whether they also have 512 GB as well or not), then 6.1 will come in at least 64 and 256 as well.
Everything else might be a bit approx or an estimate.
But it is guaranteed that if there is no 128 GB with the OLEDs, then there won't be one for the 6.1 either. The chance of that happening is as as low as the 6.1 being under USD 600. Which is negligible and can be thus considered absolute that it will definitely be over USD 600 or more, just like it will probably have the same capacities as the OLEDs, barring the 512 GB variant perhaps.
Now if the OLEDs get 128 GB, there is a high chance of the 6.1 being 64 or 128 GB whereas the OLEDs might then skip the 64 GB.
It is common sense.