Does taking chicken soup increase your semen volume?

Not true & it was started by the legendary pornstar Ron Jeremy. Here is the relevant portion from his memoir:

Samantha [Fox] continued to jerk my penis, squeezing out every last drop, then turned to the camera to deliver her final line: “Did you see that juice?” she asked. “Tigresses always get their milk.”

[....]

Jim called for the cameras to cut, and the entire crew burst into applause. I wasn’t sure if they were applauding me or Samantha, but I felt a surge of pride nonetheless.

“Holy shit, kid,” Samantha said with a wicked grin. “Where’d all that sperm come from?”

I smiled back at her, and with a completely straight face, I said, “Chicken soup.”

[....]

The real reason that I came so hard was that I held back. When I learned that I had the job, I didn’t have sex for a week. I wanted to make a good first impression, and cumming like Niagara Falls seemed like the best way to do that.

“Chicken soup?” Jim asked. “Seriously?”

It was too late to change my story now. “Yeah,” I said. “A bowl of chicken soup two hours before sex. Works every time.”

Little did I know that I had inadvertently started one of the biggest insider myths in the New York porn world. Word spread quickly around the set, and by the time I returned upstairs to get dressed, two of the actors had already sent out PAs to get chicken soup.

“Thanks for the tip,” one of them told me.

Years later, chicken soup would become a common sight on porn sets. I’d show up for a shoot and find cans littering the dressing room.

Even Samantha Fox’s boyfriend, porn actor Bobby Astyr, bought into the folklore. Whenever I’d see him, he’d invariably have a few bowls of soup heating nearby.

“Oh yeah,” he’d explain. “It makes you cum like a volcano. Chicken soup is very good for you.”

“Well, sure,” I’d say. “But not for sperm!”

'Ron Jeremy: The Hardest (Working) Man in Showbiz'
https://www.amazon.com/Ron-Jeremy-Hardest-Working-Showbiz/dp/0060840838