When a cocky self made but failing porn producer unknowingly uses stolen money to make the worlds best pornographic film, he must fight off the gangsters who claim it's their property

I have to agree with the "Fight off" part. it is vague, good call dpg.

As for what's at stake, it's the film. The film is his work and the gangsters want to take it from him. however if the film was a means to an end. (The money from the film being used to pay for his father surgery or something) it could up the stakes.

"Fight off" -- what does that mean? What's at stake? What does he stand to lose if the gangsters win? What does he stand to gain if he wins? Is he merely fighting over money? Or something more important? Is he -- should he -- be fighting for his life?

Also, what is the time setting for the plot? The present? Before the rise of the Internet?

I think this is a solid attempt. I would just take away, "Self Made" Maybe even "Cocky" Not sure if they are needed in the logline.

Also, since you identified the lead as a "Porn Producer" It will be assumed the film he is making an adult film.
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"When a failing porn producer unknowingly uses stolen money to make his film, he must fight off the gangsters who claim it's their property"
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However, your original logine is good, this would just be a little tightening.