Okay, I'm gong to use another example with some feats to show why I don't think Thor's hammer attacks would affect Thanos that much. Even though Thanos has already tanked warrior madness Thor with the powergem.
Scenario 1:
If energy shot A destroys a city, and physical punch B destroys a city, in terms of destructive power, they're about equal, yes?
If person X tanks energy shot A without any visible signs of damage, then physical punch B may or may not hurt X either, although its possible. Hard to compare since they're roughly equal in destructive power, but probably not.
But...
Scenario 2:
What if person X tanks energy blast A who's power is multiplied by 100? In other words energy blast A is now 100x more powerful than normal and can destroy 100 cities.
Is it likely that physical punch B who's destructive power can only destroy 1 city hurt person X, who tanks energy blast A who's power can destroy 100 cities?
I'm arguing probably not, unless Person X is has shown a very strong weakness toward physical punches.
This is almost exactly what has been shown in the comic. Thor used his hammer to absorb Thanos' eye beams, multiplied the power by 100 fold, and shot it directly back at Thanos. Thanos teleported right back, completely unharmed by his own energy blast who's power was multiplied by 100. If he can tank that, I think he can tank Thor's hammer without much problem.