YOU SAID:
Yes, you know that I’ve been looking at you for a long time
INTO JAPANESE
はい、あなたは私が長い間あなたを見ていることを知っています
BACK INTO ENGLISH
Yes, you know I have been seeing you for a long time
INTO JAPANESE
はい、あなたは私が長い間あなたに会っていたことを知っています
BACK INTO ENGLISH
Yes, you know that I've been seeing you for a long time
INTO JAPANESE
はい、あなたは私が長い間あなたに会っていることを知っています
BACK INTO ENGLISH
Yes, you know I have met you for a long time
INTO JAPANESE
はい、あなたは私が長い間あなたに会ったことを知っています
BACK INTO ENGLISH
Yes, you know I have met you for a long time
That didn't even make that much sense in English.