Solutions Architect Interview questions
Assuming that you mean an AWS solution architect, some knowledge about AWS will help, but they'll teach you everything about AWS. I think it's more important to be able to design the right solution to the problem and then AWS will show it's place in the solution.
Amazon is crazy about customer service and, for example, is the only company in the world (as far as I know) that will congratulate a SA if it's able to come with a cheaper solution for the customer. That will mean less money now for Amazon, but will tie the customer forever. These guys are able to see beyond their noses.
So, general design principles, general right architecture principles (minimize footprint, use standard technology easily available whenever possible, try to make it easier, simpler, cheaper...) apply and I think should be more important than the specific capabilities that AWS can offer, something that is changing very quickly and that you'll master if you get the position.