Chief is of course pronounced tʃiːf, but the letter sequence <chief> as a word ending can be pronounced either tʃiːf or tʃɪf. Here are some words with this ending:
handkerchief kerchief mischief neckerchief
Notice also the word mischievous which can be pronounced ˈmɪstʃɪvəs or ˈmɪstʃəvəs. You may also hear mɪsˈtʃiːvəs or even mɪsˈtʃiːviəs from some speakers.