I don't recall a French kiss, or Tifa actually saying she loves Cloud. She tries to tell him that, on the gondola, but doesn't actually say anything.
Tifa blushes real hard and goes on the ground banging her arms screeming NO!!! in embarasment.
This is different depending on whether you date Tifa or not. Sometimes, she simply turns away and taps her foot.

Cloud was badly affected by Aeris' death. I doubt he'd have had sex with Tifa that night. He lost a dear friend, he didn't know if the others would return to the Highwind, and he was about to face a terrible, probably deadly enemy. Most people wouldn't be in the mood.

Also, the dialogue for that night on the hill differs for the same reason that I outlined above. There are two possible conversations and events that I know of.

Cloud and Tifa probably ended up loving each other, though.