No I do actually think he is using a gel but I may be wrong. Look at shot number 2, we all know flashes put out white light, and can overpower/wash out skin tones. Now to get their skin tones close to true, you could either gel, or change your camera WB. If you change to camera WB, it affects all the other colors, so in this case everything in the photo should have a warmer tint, but I'm not seeing that. I also don't think he split toned to get their skin (highlight) to be warmer, if you check the fridge highlight directly to the right of his neck and his shirt, they are pretty much white. Not a yellowish cast you would get from split toning.