Q: These nightclubs don't fill until after dinnertime, and often only really pick up around 1:00 or 2:00am. (pick up?) とはどういう意味ですか?
A: Not a lot of people go to these nightclubs after dinner. More people go to these nightclubs around 1 or 2 AM. Pick up means get busier.


Q: "I don't like nightclubs because everyone huddles and you can scarcely walk there."

(does this sound natural?)
A: oooh ok got it 👍 thanks ☺
Q: "I never been to a nightclub before."

(does this sound natural?)
A: Very close.

"I've never been to a nightclub before."
"I haven't been to a nightclub before."
or other variations are fine.

You may also omit "before" as it's implied that you haven't visited a nightclub ever, so thus you couldn't have gone before.

"I've never been to a nightclub."

Though if you've been to one, just not in the place you're in you should use before.

"I've never been to an American nightclub before."

I add before in this version because it's implied that you have been to a nightclub, just not an American one.

Hopes this helps, if you need more help or have a question please ask.
Q: . He goes out in the nightclubs, plays poker late at night この表現は自然ですか?
A: It would be more natural to say - "He goes out to nightclubs and plays poker late at night."
Q: In these nightclubs almost %90 of people are men. この表現は自然ですか?
A: In these nightclubs almost 90% of the people are men.