An autocratic country could easily spread propaganda in the democratic country, because of “free speech” rules that most democratic countries have, but a democratic country cannot easily spread its propaganda in the autocratic country.
An autocratic country can buy an election in the democratic country, but the democratic country cannot easily coup an autocratic country.
Are all democracies are doomed to fail?
Is the future of humanity, autocracy? For the rest of humanity’s existence?
“More powerful” in which sense? Military? Propagandistic?
A “democratic” country may also install puppet governments, sometimes autocratic, as the USA did with Iran (1953), Chile (1970), Guatemala (1954), Bolivia (1971), Nicaragua (1912), Afghanistan (2003), etc.
As long as it has enemies or bigger fish that want to eat it, maybe. Playing their cards right, one could manage to get the big fish fighting against one another.