Wikipedia reports a few polls and estimates, but it's sort of obvious, if you have any acquaintance with physicists and the physics literature, that neither consciousness nor Everett worlds feature in the vast majority of what goes on in the subject. The crucial idea is that "measurement", not consciousness, collapses the wavefunction... I think a majority of physicists equivocate somewhat on whether wavefunctions are physical or epistemic, another large group explicitly consider that a meaningless question, and then finally there are those who have a thought-out personal philosophy of what QM means about reality. Anyone who believes in many worlds will be in that last group... along with the Bohmians, the "noncommutative probability" believers, and dozens of other eccentric minorities.

Have a look through a month's worth of papers in the quant-ph section at arxiv to see what I'm talking about. Papers "finally explaining quantum mechanics" (or "the meaning of entanglement", etc) are common - there are several each week - and a few of them are many-worlds papers, but only a few.