Depends on 3 factors.
1- Knowledge
2- Mindset
3- Pica's real strength
Without knowledge, Sanji would lose because he would spend time wasting his energy for nothing unless he finds his weakness sooner and faster than Zoro(something possible considering he should have great observation and is smarter than Zoro). Mindset would also be a factor because it would depend if Pica decides to go all out or not and by all out i mean taking control of the small golem or actually using the large golem. If he uses the small golem and that Sanji finds his weakness at some point, he wins. If Pica uses the large golem however, i think Sanji would lose. He lacks the scale against the golem, so if he tried to go down the stones with his kicks in order to hit Pica's real body, he either risks to end up being burried in the stones or being completely smashed to death
As for the 3, people are already giving up on Pica but the fight is not over. It would depend if it really all what he has to offer