It is a French idiom:

Plus adjective que noun/pronoun, tu meurs.

It originates from a French variant spoken in Northern Africa (pataouète) until 1962 and was later popularized in metropolitan France slang. It is recorded Dictionnaire du français argotique et populaire, François Caradec, 1977. It was likely imported by Italian speaking immigrants to Algeria because the following expression is well known since at least the beginning of the 20th century.:

Più xxx di cosi, si muore (more xxx than that, people die)

It means, of course figuratively: if you manage to be more xxx than yyy, you die (because you have exceeded what is humanly possible.)

Here, nobody can be more jealous than the person speaking.

There is a also this famous pun from Pierre Desproges, a great French humorist:

Plus cancéreux que moi, tumeur.

On the other hand, c’est plus fort que moi is another French idiom which is unrelated to the former. It means I can’t resist / I can’t help xxx.

No, it does not have anything to do with the expression "c’est plus fort que moi". You can see it as a conditional statement:

Plus jaloux que moi, tu meurs.

= (Si tu étais) plus jaloux que moi, tu mourrais.

It’s a hyperbolic, jocular expression, meaning that the speaker is as jealous of the situation as they come — to such an extent that an even higher level of jealousy (if at all possible) could be fatal. You can place virtually any adjective of your choice:

Plus + {adjective} + que moi, tu meurs.

Excusez-moi de répondre en français. Je voulais juste préciser que cette expression est bien datée : elle vient du titre d’un film sorti en France en 1982 « Plus beau que moi tu meurs » qui a connu une extraordinaire popularité.
La phrase est typique du vocabulaire d’Aldo Maccione, le caricatural playboy italien. Elle est impossible à traduire sans un idiomatisme de la langue de destination. Peut-être quelque chose comme “It’s impossible to be more xxx than me.” Elle est en général utilisée avec ironie ou dérision.