There's been indeed polls about it. I could find one in the Spanish digital newspapers El Español and the results are a bit shocking: as many Spanish people agree and do not agree with the use of force. However, in Catalonia there are 8 times more people against it. And, in fact, if you substract Catalan people from the Spanish overall, there is a 50% of people in favour of them, while less than 40% are not.
Numbers come from a poll on 800 people: 400 living in Catalonia and 400 living somewhere else in Spain.
From El 46% de los españoles rechaza las cargas policiales del 1-O y el 44% las aprueba, that is: 46% of Spanish people are against police charges from 1-O and 44% agree with them.
- Total España: overall Spain
- Reside fuera de Cataluña: living outside Catalonia
- Reside en Cataluña: living in Catalonia
- Green-ish: agrees
- Pink-ish: does not agree
- Blue: do not know / do not want to answer
Going through all the results on the poll Un 61% de españoles, pero sólo el 30% de catalanes, "aprueba" el mensaje del Rey that is, 61% of Spanish, and just 30% of Catalans, "agree" with King's message reveal other interesting details, such as 61% of Catalans seeing King's message as something that has weakened his position, while less than 30% thinks it got stronger.