Being perfectly honest, yes and no.
Vegeta's certainty on the matter definitely means they're both above Kid Gohan. The real question is by how much? That seems almost impossible to determine.
Piccolo's statement isn't as certain as Vegeta's, yes, but the takeaway is that the 2 Saiyans are more than likely not far stronger than Kid Gohan. Fairly stronger is definitely possible. A bit stronger is definitely possible.
If Goku was 12 and Gohan was 11, would Vegeta make note of Goku surpassing him? Maybe, maybe not. If Goku was 20 and Gohan was 14, would Vegeta make note of Goku surpassing him? Hell yeah.
So really, it comes down to whether you think Vegeta would bother to note Goku was stronger than Gohan if he was marginally stronger or not. To me, Vegeta's an all or nothing kinda guy. If you're inferior, then he'll say as much. If you're nearly as strong as him, he'll say as much. If you're more powerful than him, he'll say as much. I can see Vegeta and Piccolo's statement coexisting without an issue.