Almost all IITians I know of in the USA is working in the IT industry. It didn't matter which department they graduated from. American don't get tired of reminding us: "Oh, you Indians (IITians) are so good with computers." Back home too, ministers remind investors that Indians, being gifted in mathematics, are ideally suited for software jobs.
They go into many industries. Some go into IT, but many go into investment banking, law, marketing and so on. Most IITians don't get that chance. If they don't want IT jobs they are free to go back to India where most likely they will end us writing software programs for some American company.
Related link: IIT and IITians at Microsoft