Aside from being one of my favorite fetishes....

A latex fetish is also called a Rubber fetish. Best defined as a specific sexual attraction to people wearing rubber/latex, or in certain cases, to the garments themselves. Closely related to rubber fetishism is PVC fetishism, related to shiny clothes made of the synthetic plastic polyvinyl chloride (PVC), also known as vinyl.
One reason why rubber and other tight shiny fabrics may be fetishised is perhaps that the garment forms a "second skin" that acts as a fetishistic surrogate for the wearer's own skin. Thus, wearers of skin-tight rubber or PVC garments may be perceived by the viewer as being naked, or simply coated in a shiny substance like paint. Rubber and PVC can also be polished to be shiny and can also be produced in bright colours, adding further visual stimulus to add to the physical sensations produced by the material. The tightness of the garments may also be viewed as a kind of sexual bondage. The smell of latex rubber is also a turn-on for some rubber fetishists, and such garments are usually impegnated with chemicals to enhance the odour.
However, some rubber enthusiasts are also turned on by the wearing of draped rubber garments such as cloaks. Other rubber paraphernalia, such as gas masks and Wellington boots, are also often added to the scenario. Some PVC enthusiasts are turned on by PVC Hazmat suits and other forms of industrial protective clothing.

Rubber fetishism often involves dressing up in the material, or looking at it worn by sexual partners, or fantasies about wearers of skin-tight or other rubber garments, such as divers and workers wearing industrial protective clothing. Another common stereotype of is the image of a dominatrix wearing a skin-tight rubber or PVC catsuit.
For hygienic reasons, many sex toys such as dildos and butt plugs are made from rubber or similar materials, and this is also a factor in rubber fetishism. Some rubber fetishists are also medical fetishists or have an interest in klismaphilia.
The "Batman" films made heavy use of rubber and PVC imagery for Batman and Catwoman's costumes respectively.

Gas mask sexual fetish is often combined with the use of other sexual latex devices, such as, among others, Vacracks.
What do you call a person with a latex or rubber fetish?

Well that's quite simple - they will call themselves a rubberist.
No one knows how many rubberists are on the planet but the hundreds of manufacturers and sellers that serve the rubberist market would suggest the number is probably surprisingly large.
Surveys by the International Association of Rubberists indicate that rubberists tend to be well educated and reasonably successful in life. They also indicate these people tend to enjoy their fetish and do not generally regard it as an affliction.