Which subway station is Eiffel tower? And how to get there from the airport in the night?

Question

Charles de Gaulle airport

Answer 1

David's answer is fine, except for the fact that the section of the RER line is currently closed for repair work. I think until 15 August.  

Answer 2

Bir-Hakeim (line 6) is the closest métro station. Champ-de-Mars Tour Eiffel is the closest RER station. As for getting there from the airport, are you coming from Roissy Charles de Gaulle or Orly?

EDIT: From Charles de Gaulle Airport, simply take RER B southbound (you don't have to worry about going the wrong way, because you can only take it south from there anyway) to Saint-Michel Notre Dame station. Then transfer to RER C (going towards either Pontoise, Argenteuil, Versailles, or Saint-Quentin-en-Yvelines- it doesn't matter which, since you'll get off the train before it splits to serve those different destinations), and get off at the aforementioned Champ-de-Mars Tour Eiffel station. http://www.aparisguide.com/maps/rer.htm

EDIT 2: Changed "Saint-Martin d'Étampes" to "Saint-Quentin-en-Yvelines" in the preceding directions- the former would have you going the wrong way! Sorry about that- looks like my map-reading skills are slipping- either that or my brain is fried here at work and I need to go home...

EDIT 3: SOTIRES- I didn't know that. I haven't lived in Paris in over 7 years. However, I have to assume that there are buses to replace the portion of the RER line being worked on?