Yes. But not on the basis of caste, religion or sex. The only reservation in BITS Pilani is for the students of Birla School and for those students whose parents are faculty members.
But, now comes the important part, the students are only offered MSc courses and that too, not of their choice. Also, they are not allowed to opt for dual degree.
Also there are very few cases as mentioned above. Thus, this is not mentioned anywhere on the website and not of any impact on the admission if other students.
Hence, this reservation is totally different than the one in IITs and NITs.