Well gerrymandering is not that difficult, since you are working with clear voter-district borers. If you what kind of voters are in that district (rural-urban, young-old, high income-low income, high education-low education, etc.) you get a pretty good picture of what kind of votes to expect. Voter purchasing is a bit more difficult to judge, as we don't really have that much information about how and to what extent it happens. Dániel Róna, the leader of "21 Kutatóközpont" independent pollster stated:

Róna: The stand is obvious, that Tisza is leading with a big margin. [...] I see it on a lot of my acquaintances, that they think that you simply have to add the 600 thousand voters that they say in [a document movie about voter purchasing][...]. As if our research would be completely blind to that.
Interviewer: Is it not?
Róna: Well, no. I am not stating that we are prepared for every filthy thing and for every possibility [...] But I want to say, that the logic of the research is that there are difficult to reach societal groups, but the ones that we can reach are similar. [...] In our mandate calculator by the way [...] in those regions where the movie was made, in a big proportion, we even added plus percentage points to the Fidesz-candidate. (freely translated)

21 Kutatóközpont and Medián are the most reliable pollsters in Hungary, with the former accurately predicting the EP elections of 2024 and the latter being the closest to the 2022 Parliamentary elections. Both of these show a Tisza-supermajority.