It's very unlikely that Gohan is stronger than Android 17 at this point.
Android 17 has numerous feats that more than support the notion that he is SSB-tier. Below are a few examples.
-Pushed back an attack that five SSB-tier fighters (Gohan included) were helpless against.
-Performed far better against Base Toppo (a fighter that was implied to be on par with SSB Goku Kaioken) than Gohan.
Ultimate Gohan was practically useless against Toppo; despite getting in a sneak attack he was thrown around like some weakling. Android 17 actually attacked Toppo head on and was even able to push the Pride Trooper briefly in hand to hand combat; a feat that Gohan was not once able to pull off. Just this bit alone strongly implies that Android 17 is a good deal stronger than Gohan.
-Android 17 completely wrecked Toppo during their beam struggle. Even though Golden Frieza was helping, Android 17's blast seemed to have caused most of the damage; it engulfed both Toppo and Golden Frieza's blast before nearly destroying Toppo himself. What did a surprise Kamehameha from Gohan do to Toppo? Absolutely nothing! Toppo tanked it like it was a joke, while he couldn't even take his hands off of Android 17's blast during their beam struggle. He even charged up his red aura before said beam struggle, which once again implies that he took Android 17 far more seriously than he did Gohan. The only other time we saw Toppo flaring his aura was when SSB Goku flared up his Kaioken.
Even Frieza indicated how Toppo was unable to fight back during the beam struggle. If Android 17 was really that much weaker, Toppo would have just tanked or moved away from Android 17's blast while making Frieza his priority. Neither one of these things took place because he was stuck in the beam struggle with #17 and even the slightest of movements would likely leave him heavily damaged.
So in short, Toppo tanks Gohan's blast like it's nothing, while Android 17's blast requires his full power to fend off.
-While Android 17 and Gohan both fought SSB Goku, the circumstances were a tad different. Goku didn't intend on using SSB against Android 17, while Gohan had to urge his father to use said transformation. Goku also mentioning how glad he is that Android 17 is no longer an enemy says a lot. For those words to hold any meaning, Android 17 should at least be current SSB-tier, as anything less for a Goku that can easily use Kaioken x20 on top of SSB would be a joke in the long run and certainly not worthy of such acknowledgement.
For those who may be wondering why Android 17 didn't just use his his SSB-tier power to flick away opponents who are seemingly base saiyan level...
Goku and Gohan can visually showcase approximately how much power they are utilizing with the usage of transformations. Android 17 on the other hand cannot transform; and therefore, it is difficult to gauge what portion of his power he is using against a given opponent. This in-turn makes it far easier to label him as having inconsistent feats; but from a writing standpoint, #17 flicking away these so-called base saiyan-tier opponents right from the get-go would be the same as Goku using SSB from the start and clearing out the fodders in a matter of seconds.
Also, saying Android 17 is only as strong as he is because his barrier is no different than saying Goku is only top-tier because of his transformations; these attributes are part of their powers and abilities and thus shouldn't play any role in devaluing their strength.
The power scale below basically highlights where I feel Android 17 and Ultimate Gohan stand in.
Base Toppo = SSB Goku Kaioken (2-3x) > SSB Goku > / = Android 17 > Ultimate Gohan >>>>>>>>>>>>>>> SSJ Vegetto (Buu saga) > Buuhan > Buutenks > Ultimate Gohan (Buu saga) > SSJ3 Gotenks > / = Super Buu > Mr. Buu
SSB Goku Kaioken x3: 300
Base Toppo: 200-300
SSB Goku Kaioken x2: 200
SSB Goku: 100
Android 17: 90-95
Ultimate Gohan: 75
SSJ Vegetto (Buu saga): 0.1