There was a member on here feeding her cat the canned 'shred' style cat food. She would mix a tiny bit of the pate into the shreds. Make sure her cat would eat that for a few days. Mix a tiny bit more pate in, a little less shreds. Sometimes, she would have to go back to a previous combination of the two foods to get her cat to eat.
It took a while, but eventually her cat did transition and eat only the pate style food. This was member Jamie & Jupiter. It took a full month to work through this food change.
There are also some good tips and tricks here to get a cat to eat a different food type. It was written for transitioning a cat from dry to wet food but the same tips and tricks work for a change from shreds to pate style or chunky to pate.
http://www.catinfo.org/docs/TipsForTransitioning1-14-11.pdf The idea is to make the pate style more tempting, more appealing for your cat then the other gravy style.
There are also some of the Fancy Feast non-pate styles that are low carb. Try the Tender, Chunky, Flaked, Kitten varieties.
Do you free feed or meal feed? Yes, it is important that your cat eats, but they need to be hungry to want to eat something unfamiliar.
Some tricks that I used with my foster cat Wink are: heat up the food to mouse body temperature, sprinkle parmesan cheese on the food, pour a little tuna water over the food, crumble a freeze dried chicken treat like the Halo Liv-a-little treats or the Pure Bites on the food, switch to meal feeding, put dish down for 20 minutes and then remove. Try the food again in a couple of hours.
If free feeding now, maybe try to get him on a meal feeding schedule first, then try for lower carb food. Let his natural hunger work for you in this process.