No, Ukraine should not surrender because if they surrender now the same argument can be made next time - and with Russia there will always be a next time. This is an existential fight for Ukraine and Ukrainians.

Assuming that you are arguing in good faith you should read up on some basic game theory. The outcome of this fight is not just about this war but about establishing the incentives of all future potential attempts at aggression by Russia (and other expansionist countries).

Edited to remove the snark.