Be very careful with this phrase. I said it to a Polish girl once. We are married now!
I am trying to correlate Russian and Polish here. "Ciebie" instantly came to my mind as "тебя", and it's "you" (ты) in the accusative case. "I love you" is "Я люблю тебя". So why is it "Kocham cię" in Polish, and not "Kocham ciebie"? What case is this?
They are both correct in this sentence. But in general meaning 'ciebie' is a stressed pronoun, while 'cię' is mute (i think these are the English terms, correct me if I am wrong).
I am not so good in explaining Polish grammar, (and it was long ago when I was learning it), so let the Polish Language Council speak instead of me: ;) The only cases in which you have to use longer (stressed) pronouns:
In the beginning of the sentence ( "Ciebie kocham" - "It is you whom I love")
In the end of the sentence when it has to be stressed that this person is the real receiver of the action ("Kocham ciebie" when someone implies that someone else is the real object of affection ;)), or in the middle, but followed by an explanatory sentence ("Kocham ciebie, a nie ją" - "I love you, not her").
When the pronoun is the only word in a sentence - "Kogo kochasz?" "Ciebie".
I hope it is more clear now.
(Sometimes it is hard to explain rules, that you know since your childhood)
It is correct, although sounds weird. While saying that, you stressed 'you', but in the position of the sentence, instead of using the stressed case, which is 'ciebie'.
Ok, I know the proper answer is "Kocham cię" but when replying, why polish people use "Ja ciebie też" instead of "Ja cię też"?? It's like for example if somebody says "Jest mi zimno", the reply would be "Mi też" so it follows the same case... Kinda confused with this "Ja ciebie też" XD
It has to do with emphasis. In kocham cię the emphasis is on the word kocham ("I LOVE you"). Ciebie is an emphasized version of cię. "Kocham ciebie" would mean "I love YOU" or "it's you I love". So when answering, it seems to be more common to say "and I (love) YOU" instead of "I (LOVE) you".
If somebody says "Jest mi zimno", the reply must be "Mnie też". The only form in the beginig is the long, stressed form.
A girl from Kraków told me that, and that's the reason I'm studying Polish. :)