what benefits might government officials have if positions in china were based on examination results rather thsn family ties

It depends if the government officials have access to corrupt patronage or not.

Explanation:

With the liberalisation of the economy in stages, after the death of Mao in 1976, and the defeat of the Gang of Four, there was an explosion in economic opportunities, channeled through a political dictatorship.

This gave unprecedented access to the Chinese elite, i.e. within the communist party to make vast fortunes, with little or no accountability.

If China was more meritocratic, as the question implies, then positions across Chinese society, including government officials, would be based on ability not connections.

However given that most government officials, particularly in senior posts, will be in the communist party already, then the impact of examination results might not be crucial.

The real question is giving access through meritocracy to all sections of Chinese society. That needs fundamental  political reform.

could you go a bit more in depth with you question? it's quite hard to understand. as soon as you do that i will be glad to : )