I think there is a correlation between strength and gateway size, but ultimately it's the level of Talent that dictates more than anything. Seems to me Talents would follow the same general distribution as strength with most channelers having the Talent at around 50% of maximum and outliers on either end being exceptionally strong or weak a la bell curves. Thus most people would possess an average Talent and require a minimum of 19 strength to power the weave. Higher talent would allow a level 19 to make a larger gateway and obviously also give weaker than 19 channelers the ability to make the weave work with less power.

Much like Healing, exceptionally gifted channelers (i.e. High level talent) can manipulate and modulate the weave in ways others cannot. Yukiri being able to place them sideways and above battlefields, Androl and his giant gateways. Flip side of this is Damer struggling and needing to use more OP to generate a useable gateway, despite his greater strength ... He probably has a slightly less than average talent since he can still make the weave work. I suspect there are some who possess such a weak talent that even if they had massive OP strength they may not be able to make a useable gateway.

Thus two channelers of roughly equal strength may still be able to generate roughly equivalent gateways in terms of size, but using different amounts of OP to achieve this. But Logain wouldn't see this because the majority of Channelers have the level of Talent required to make a useable gateway that is outwardly commensurate to their strength. Thus seeing a man like Rand make a somewhat larger gateway seems to indicate to Logain that Rand is stronger, when in fact he likely possesses a better Talent for Traveling

Let's say, for arguments sake, that the gateway average (i.e. Large enough to walk through) is 7'x4' and requires strength of 19 to create. Then assume that an average Talent acts like a multiplier, in this case 1. The way I see it, a very strong talent, let's say a 2x multiplier, would allow a level 19 to create a gateway of 2x the size (i.e. 56 sqft) or would only require 50% of the strength normally necessary to create the 28 sqft gateway I mentioned above. Meanwhile a very weak Talent .5x multiplier would require 2x the amount of OP to open a 7x4 or would only allow for a 14sqft gateway. Thus Androl might possess a 3x or higher level of Talent multiplier which would mean he would hardly need any strength to create large gateways

Thus a woman as weak as Daigian with a strong 2x multiplier could create a 28sqft gateway and a man even weaker with an even larger multiplier, maybe 5x, could create gateways larger than Rand with just a dribble of Power.