Smith has undergone the mandatory NFL concussion testing after knocking heads with Steelers rookie running back Le'Veon Bell, who also suffered a concussion.
"Jimmy seems to be doing really well," Harbaugh said. "He was doing well right after the game. He's going through the concussion protocol now. That was what it was during the course of the game, but everything looks really, really good for Jimmy.
"Should be fine. You never know with that, but it looks like he's going to be able to even practice on Wednesday, so we'll be feeling good about that."
Meanwhile, Harbaugh said that the decision on whether tight end Dennis Pitta (right hip) will be activated from the injured reserve-designated to return may not come until the end of the week.
This is the week the Ravens had originally planned to activate Pitta, who's been making excellent progress since undergoing surgery after dislocating and fracturing his hip on July 27.
"It'll probably come down to the end of the week," Harbaugh said. "I've got a pretty good idea that he's doing well. It's just a matter of how well - you know, is he feeling good enough, do the doctors feel like he's ready to play. That's what it's going to come down to.
"So, he ran around well last week. You guys know that, and we'll go through the week this week and see how he does. If he can play, he will, he should. We want to get him up, that's our goal. But he's not 100 percent certainly at this point."