This is a tough one for me to predict honestly. I think it's hard to look at totally objectively and not considering the history/context....I think if these were two totally anonymous teams - take away the names, the history, the jerseys, etc - and you compared just their performances this year, you'd be hard-pressed to favor the 49ers.
They do have a good offense (in terms of yards per game) but other than that, I think they're getting by a lot on name recognition and reputation at this point. They're a .500 team who hasn't beaten a single team with a winning record this year (Jets 3-8, Patriots 3-8, Seahawks 5-5, Cowboys 3-7, Buccaneers 4-6). Their line (on both sides of the ball) is just so-so. They have a bad run defense, and an average pass defense. At this point the DL is basically Nick Bosa and a bunch of "replacement-level" players. Same story on OL - It's Trent Williams and who knows. They've got a good run-blocking OL, but an average pass-blocking one. Deebo Samuel, for instance, is one of those names who I think people still put a lot of respect on and are pretty scared of, but he's been awful this year. He's averaging less than 60 all-purpose yards per game and has two TOTAL TDs on the year.
But of course the game is not played in a vacuum and context matters. If we play like we played vs Chicago, we'll probably lose. Still, looking at the totality of it...if you took our "average performance" from 2024 and played it against SF's "average performance," I think we'd win. Honestly, if you break down the numbers (again, just on average), we're almost identical, but we have played a considerably more difficult schedule (We are currently 8th in SoS played; SF are 22nd)
One random thing working in our favor is that in general we play better as the game goes along. Our 4th-quarter defense has been really good on the whole...But then SF has been the opposite. Their defensive EPA is #4 in the 1st quarter and #7 in the 2nd quarter. Then you get later in the game and it's #13 in the 3rd and falls off a cliff to #28 in the 4th.
So, I don't know. My head says we "should" win, but my gut is not confident...