It is not recommended to feed cats jello or any other sugary and high-fat human foods. Jello is a sweet and sugary dessert that contains a high amount of sugar and calories, which are not well-suited for cats' digestive system. Feeding cats jello or any other sugary and high-fat human foods regularly can lead to weight gain, digestive issues, and other health problems. Additionally, some types of jello may contain artificial sweeteners, such as xylitol, which can be toxic to cats. Therefore, it's best to avoid feeding jello or any other sugary and high-fat human foods to cats and stick to a balanced and nutritionally complete cat food recommended by a veterinarian. If you want to provide your cat with a treat, it's best to choose a healthy and cat-friendly snack, such as a small piece of plain cooked meat or a small amount of cooked vegetables, after consulting with a veterinarian.