I don't claim to be an expert, in fact, I outright disclaim it. Having stated that, Here's what I think.
It's extremely unlikely for a lit cigarette to ignite gas fumes while filling your car. It's just a common sense precaution to prohibit smoking at gas stations. it would take a bizarre situation, not just smoking, to create a fire. You can throw a lit cigarette in a puddle of gasoline, and the only thing that will happen is the cigarette will be extinguished. The gasoline can't be ignited, only gasoline vapors can. But even then, the gasoline vapors must be in a fairly narrow ratio with air, and with an ignition source, to ignite. A lit cigarette is not an ignition source, a spark or flame is. You would have to spill gas all over the place, then use a lighter very close to the spill, to even come close to starting a fire. Or light a cig very close to the car where the gas hose is, and have absolutely no wind or air movement, to start a fire. People smoked all the time at gas stations when I was younger, and I never heard of a resulting fire.
As for vaping. While I'm sure no one would like observing that activity, IMO, it's unlikely to start a fire. Unless, you tried real hard like I just described. Even harder in fact. Because the coils get hot in an enclosed atomizer, it would probably be virtually impossible to even intentionally start a gas fire. You would have to create a spark between your battery and atomizer. And have the proper gasoline vapor/ air ratio.
best regards, larry mac
p.s. (this is factual, anyone can easily google it) The lower and upper limits of gasoline vapor to air must be between 1.4 and 7.6 %. That means 1.4% gasoline vapor and 98.6% air, up to 7.6% gasoline vapor and 92.4% air. Any less, or more and it can't be ignited at ambient temperatures.
p.s.s. I've personally smoked, and now vaped, many many times at gas stations.