What will be the expected cutoff?

First be specific, about Category(Gen/OBC/SC/ST/PWD), and course ,you want to know,
2015 cutoff for various courses in almost all IITs.

Cut Off For Open Category
Construction Planning & Management— at least 70+ marks
Structural Enginnering— 50–55+ marks
Geotechnical Engg- 55–60+ marks
Environmental- 45–50+ marks
Transportation- 60–65+ marks
Hydrology- 45–50+
Energy Management- 40+ marks
Irrigation- 50+
Geomatics- 65+
Marine- 48+
Ocean- 45+

One final thing, these are the cutoff only for preparing a list of selected candidates, who will be called for further process.
Admission in the course depends solely on number of candidates applied. For some courses they can offer you direct admission, for some only interviews and in rare case they can have both written test followed by an interview.

But at the end do not think about cutoff, scoring good marks always removes the “if-else” option from your choices.