They can have a similar pronounciation when the "i" modifies some other vowel. An "i" on its own (vowel) is different from a "j" on its own (consonant), though the mouth position is not so different (but there is a difference). In Chinese, you don't notice the similarity because of the consonant-vowel-consonant syllables.
Kind: "i"
ist: "i"
Jäger: "j"
Dia: "i-a"
Maier: "j"
Leier: "j"