I don't see him saying anything of the sort. I can see is him saying the new model is higher resolution.
What is the implication? Nothing. These are just two points of data. One may posit that Canon is entering into a new era of resolution. Maybe we'll see that 120MP APS-C sensor be packaged for market. Maybe not.
Better in terms of what? Resolution, DR? And why is hard to believe? 7Dii is priced higher for build quality, speed, AF, not for the sensor. All Canon cropped sensors of the same generation are more or less the same. You need bigger sensor to see substantial image quality improvement.
If the only metric is the resolution, then 24 megapixel is better than 20. But that only goes for low ISO. ISO 1600 T6i sensor lost any advantage, as the noise "eats" the sharpness.