Going by your phonetic transcription:
- the vowel in "Tuh" actually doesn't exist in Japanese, so it'd be hard to mishear it as another word Japanese word, it'd just sound like a very American pronunciation of the Japanese "ta", so it shouldn't cause an issue.
- "Kay" (rhyming with "Hey") is actually fairly close to the right pronunciation of "kei", it just sounds a bit American, but not like a different Japanese word.
So, from the information you've provided, I see no reason the pronunciation could sound like a different Japanese word.
The closest Japanese word which means 'money' that I can think of is お金 ("o kane", recordings available here), but that's pretty different -- it doesn't have a 't', it has an 'n', and the final vowel is shorter, so your friend would have really need to have butchered the name for it to sound like that.
(Another related word might be 高値 (takane), but that doesn't mean 'money', it means 'high price'. And still, it has the 'n' in it.)
EDIT: Okay, based on your edit, "ki" (rhyming with "hi") would result in a different Japanese word: 高い (takai). This doesn't mean "money", it's a very common word which means "high" or "tall", though by extension is often used to mean "expensive". Maybe this is what your friend said?