I know they changed the C to a K but they have Camel cig's that do spell Camel with a K. Would this be considered copyright infringement? How does vapor4life get away with this?
It's not copyright infringement at all, because names can't be copyrighted. It could be argued that it is trademark infringement, though, and changing the "c" to a "K" is an attempt to avoid infringing.
Trademark infringement is a little fuzzier than copyright -- direct copying is not necessary. The test is whether or not a reasonable consumer could confuse the products and mistakenly buy one, thinking that it is the other.
Juice vendors are likely to be on pretty safe ground here. There is a slim chance that they could even get away with calling it "Camel", although that is a close enough legal call that they would go broke defending themselves in court regardless of the legality.
In any case, they're almost certainly safe calling it "Kamel," as there is no possibility of consumer confusion. Now, if Philip Morris (or whoever makes Camels nowadays) got into the e-juice business, all bets would be off.