Can I take IELTS to make up for failing TEM-8?

This situation cannot be remedied by IELTS.

TEM-8 and IELTS are two different tests. If you fail TEM-8, IELTS can't make up for it directly. However, if you need to prove your English ability, IELTS score is an international proof method, which can play an important role in studying abroad and immigration. Therefore, if you need to prove your English ability, you can consider signing up for the IELTS test.

If you really want to test IELTS scores to improve your English and help your future development, it is also worth a try. In any case, test scores are only one aspect, and you need to improve your language ability through a lot of reading, listening, speaking and writing exercises.