It's worth noting that the party vote share here was 53% for Tisza vs. 44% for the even-more-right-wing parties. The fact that this results in a two thirds majority is because the electoral system inflates the strongest party. Orbán has previously achieved two thirds majorities multiple times while winning less than 50% of the party vote. Most seats are assigned not through party lists but in single-member constituencies with first-past-the-post voting, same as in America. So it's not "convince two thirds of the people to vote for you", it's "convince a very slim plurality in two thirds of the constituencies to vote for you".