On this page, you can learn Japanese grammar to talk about what many people think.
Many people think + sentence
sentence + と思う人は多いです
The sentence in front of と思う人は多いです must finish with Plain Form.
Many people think that Japanese people eat sushi every day.
Many people think that Japanese cars are wonderful.
‘Many people think’ in Japanese is ‘たくさんの人々（ひとびと）は思います’, so it is not wrong to say とたくさんの人々は思います instead of と思う人は多いです.
However, と思う人は多いです is more natural.