"Like father, like son."
Translation:Kia patro, tia filo.
Kiel means "in that way" as an adverb, whereas "kia" and "tia" are adjectives. When you describe nouns, you use those as qualifiers. In this case, you're really saying "however the father is, thus is the son" which is why you use "kia" for the first, and "tia" for the second.
without any further context, then either answer is correct. "like father (does), like son (does) would use kiel/tiel.
It's ok to use "kiel" but the second "like" needs to be translated as "tiel".