As previous answers have made clear, BITS Pilani is now listed in the QS World University Rankings. International rankings are an iterative process, each year taking a fresh look at contending institutions that deserve to be included, and included institutions that ought to be displaced. For the most part, universities from India struggle in international rankings relative to their domestic reputation… this is usually because they are extremely teaching focused and thus their research is either lesser in volume, or in international recognition and influence, or both.
In recent years, leading private institutions in India have set about changing this and thus more have qualified for inclusion, and more may do so in future.