Hi

First of all IIT is not a stream to be chosen in your class 11th , IITs are just an Engineering colleges which provide admission through JEE advanced so I am guessing that you mean that you are in 11th and have to chosen science stream maths group and you are preparing for JEE mains and advance for pursuing engineering in IIT.

And yes,
After your engineering from IIT you will  be able to become an IAS officer as to become an IAS officer you need to clear UPSC civil services examination and to be eligible for that you need to be a graduate in any discipline doesn't matter whether it's Engineering or any other graduation course fr om any recognised University

After the completion of your engineering you will be eligible for UPSC examination and can appear for it and you will have to go through 3 stages of UPSC which are listed below :-

*The first stage of the exam is Preliminary examination (objective )

*The second stage, Mains (written).

*If you manage to clear both prelims and mains then you are to go through third stage i.e interview/personality test .

And if you managed to clear all the three rounds mentioned above, then  you can become an ias/ ips etc officer on the basis of rank obtained by you in UPSC and your preference

Also,
These days it has been become very common to go for UPSC examination after engineering, a lot of students complete their engineering and then go for writing UPSC examination and not only appear for UPSC examination, they qualify it as well also and some even top the exam : ) .
For Instance, Kanishak Kataria  who topped  UPSC civil services examination in 2018 was an engineer.

The additional benefit of  doing engineering first and then appearing for UPSC examination is that you will have a back up, you know UPSC examination in note that is easy to crack show in the worst is if you you could not crack it then with your engineering degree can go for other decent jobs.

In short,
You don't need to worry at all after engineering from IIT you can definitely become an IAS officer

Now that ,you are in 11th and preparing for JEE ,to prepare well you can go for our jee program at the convenience of your home, the link for the same is provided below

https://learn.careers360.com/knockout-jee-main-april /

Thankyou