Is it possible to become a mangaka?
Yes! You can become a Mangaka even of you aren't Japanese if you format your manga Japanese style and publish in Japanese in japan. You can become an __-mangaka (British, Australian, American,etc) if you produce in those countries. A Manga artist or mangaka is someone who draws or otherwise creates manga.
What does it take to become a mangaka?
They draw the characters and scenes for the comics, and many also create the story line. If you want to be a mangaka, you first must gain experience as an artist. Most mangakas get their start by creating their own comics and then presenting them to manga publishers and magazines.
Can a foreigner be a mangaka?
It's without a doubt possible to become a mangaka as a non-japanese. And there are quite a few people who have done it. Mostly they are from Korea or China, but there are some from U.S. as well. I'm not entirely sure if Shonen Jump publishes foreigners mangas, but many other publishers do, so I imagen it does as well.
How much does a mangaka make?
On top of this, they still earn their royalties, which is around 10-15% per tankobon. These tankobons sell around $5 each which would make ~$0.50 a tankobon. Given that it takes around 5 hours for a page, we can say that an average starting mangaka earn about 5$ an hour.