Why does he want to do this? Is it because he's interested in engineering, or because he looks up to you? As an older sibling, I have also faced this problem. Cases in point: Little sister wanted to do cross-country running like me, was terrible, tried swimming instead, became three-time All-American. Little brother wanted to be good at math like me, didn't get it, and now plays piano, guitar, drums, and sings at church instead. Still needs help trying to get Audacity to do what he needs. They wanted to be like me, but had different talents. My girlfriend's little brother, on the other hand, truly wanted to be an engineer, He imitates me and seeks me for help, but his dream is his own.
I'm also going through school for computer/electrical engineering, and I see others dropping out all the time. This is the nature of technical schools. Your desire to prepare him is a good thing, but you both have to accept the possibility that he may not make it.
If he wants to go to the school you went to, I'd actually suggest starting him out with C. If he can have an understanding of what happens behind the object-oriented scenes, he'll have a big leg up on his peers. More importantly, his ability to learn a language and to understand programming and computing concepts is what you need to evaluate. These skills will end up being much more valuable for him than knowing the syntax of Java or C#.
While your school may have prepared you to program in C#, is that his goal? If he is likely to get a further degree, to go into electrical or computer engineering, or to use a language not taught at either school, I think that the other school might be better suited to his career path. His choice of schools may also help you determine whether he's just imitating you, or whether he really wants to become a programmer.
If he's not mature enough to realize that (1) his dream may not be his own-he's just following you, and (2) failure is a possibility, then I don't think he's ready for either school. Give him a year to prepare and make some money to pay for school, so he can learn one or two languages and getting any math skills he may be lacking, and then he can enroll and be successful.