Yes, as usual, a small sample of input records or your current script would really help to help you.
I don't think you need the double quotes at all, but even using double quotes should work just fine:
LOAD * INLINE [
"KT Kasse / Kunde", "KT Kasse/ Kunde"
"KT Konditionen / Provisionen", "KT Konditionen/ Provisionen"
LOAD MapSubString('MAP', TXT) as Output, TXT INLINE [
KT Kasse / Kunde
KT Konditionen / Provisionen
asasKT Konditionen / Provisionen Blabla KT Kasse / Kunde
edit: and looking at the title of your post, what about the nr. of lines in your inline table?
Don't really understand this title in combination with the body of your post.