No, they don't help. Unless you know the basics of Japanese (1 to 3 years of taking Japanese) watching anime will not be able to help you learn the language. It might be different if you are Chinese which Japanese borrows from, but if you're going from English to Japanese, it won't help you much at all XD I took Japanese in high school, it's a very different language from English

If you want to learn a different language, take a language course. If you use anime as your only point of reference for anime you end up only learning to speak weaboo... ugh, flashback to the anime clubs back in high school x~x

I think watching movies and such should be part of your strategy to learn the language, but in no way the main way of learning. Obviously you need to be taught the basics, such as a language course.

Although not always viable, sometimes the best way to learn a language is to go to a country that speaks that language, like China or Taiwan.

I found however that after you learn to speak the language, you can use mandarin subtitles on mandarin shows to learn to read the language.

Mandarin is not too hard grammatically. The things people I see usually find challenging is memorizing all the words and differentiating between different tones. Hardest part would be to learn to write it. I just hope you don't need that.

If OP's goal were to be able to speak some Mandarin then by all means he can try to learn from subtitled noneducational content but it remains a big stretch to do so and I don't recommend it either ...

If OP's goal included reading or writing some Mandarin then doing what non-Japanese language educated anime fans are doing won't help one bit on that ...

No. It won't help if you're trying to learn it to live or write it. Even after watching Anime for 15 years. I still can't watch a show fully, without subtitles. I also have to read up on a lot of the text. I remember Katakana easily. But Hiragana/kanji, nope. You gotta learning it through proper schooling.

unfortunately it won't teach you much s some translators think they are the next JK Rowling and sometimes flare things up than what is said.

plus sentence structure different to English.

you will learn common words though

reading the subs!

It helps if you're learning Japanese. Not so much if you don't know any Japanese then you learn a couple words and phrases but you learn absolutely nothing about grammar and particle usage if you're just watching.

You only learn some words or expressions. I have finished like 200 series and when I watch without subs I understand like 30% of everything.

I dont think it's a good method for learning a new language