I doubt that, as a preliminary matter. Republicans have gerrymandered in some states, such as Indiana and Texas, but Democrats have done so in their own stronghold states at least as much. And gerrymandering is immaterial to the control of the Senate.
But even if you were correct, I would still want gerrymandering stopped. It's not fair, no matter who benefits.
It starts at the state legislature folks. My experience with "non-partisan" redistricting (see: New Jersey) is that it eventually becomes dominated by poltical hacks of one party or another anyway.
No offense to Californians, but how come you guys always feel the need to make a friggin "ballot initiative" out of every issue instead of voting for those who represent your interests, which is what a REPUBLIC is all about. Just curious...