Yes, domestic cats do vary in intelligence. The same must apply to the wild cats. I can say with confidence, however, that domestic cats vary in intelligence based upon tests carried out on dogs. I know that is not what you want to hear but we are reliant on dog studies sometimes to extrapolate i.e. work out what may be happening with cats. We have to do this because so many studies are conducted with domestic dogs in preference to domestic cats because they’re much easier to work with. The second reason why I can write this with confidence is because common sense dictates that cats vary in intelligence like people. They can be no logical reason why cats should not vary in intelligence as humans. The physiology of cats and humans is similar, we are both mammals with broadly the same anatomy at a fundamental level.
A recent study published in the journal Scientific Reports tested the intelligence and memory of two domestic dogs with known high IQs. One of them, Vicky Nina, is now deceased and at the time she was a media sensation with a remarkable memory. She came from Brazil. The other canine with a mega-brain is still living and his name is Whisky. Whisky is a border collie from Norway.
The researchers concluded that these dogs had a similar intelligence and ability to memorise language as a 3-4 year-old child. They were presented with a new toy and the human mentioned the name of the toy four times. They then placed the toy amongst many other objects and asked them to retrieve it by name. They were able to do so. The researchers concluded that they had learned this ability quickly but decided that it was rare among canines.
Dr Fugazza, a co-author of the study and one of the researchers, said that Whisky was a gifted dog and unsual. Whisky is four years old and Vicky Nina was nine when she carried out the experiments. They took place in 2018. It appears that their memories faded quite quickly but the researchers decided that if they played several times their memories would have been extended.
There appears to be two conclusions that we can take from this research, (1) there is quite a strong variability in intelligence among domestic dogs and therefore I conclude the same must apply to domestic cats, (2) the intelligence of the more intelligent dogs is similar to that of human children, in terms of acquiring vocabulary, who are in the age group 2-3 years of age.
The other co-author is Adam Miklósi, head of the department of ethology at Eötvös Loránd University in Budapest at which the study took place, as I understand it.