I'll cite a number of polls (election results and opinion polling) which have been conducted over the years.
In 2010, a Times of India (TOI) poll found 58% approval for Naxalites in the state of Andhra Pradesh, which is one of the regions where the group is active. In the state of Telengana, the same poll found lower support for the rebels, writing:
An exclusive survey of the once Maoist-dominated districts o An exclusive survey of the once Maoist-dominated districts of the Telengana region by IMRB, well-known market research organisation, for The Times of India has found that while attitudes towards the rebels are ambivalent, the condemnation of the government and its means of tackling the problem is quite clear.
The TOI says it wanted to do more surveys in Naxalite strongholds but decided against it because the areas are difficult for pollsters to ener. The focused on the aforementioned regions instead. Other results presented in the article are:
Those answers are buttressed by the responses to three other questions. The first of these was on whether the characterization of the Naxals as extortionists and mafia was accurate. Two-thirds disagreed. An elaboration of this came in response to a slightly more open-ended question. Over half said the Naxalites worked for the good of the area, another one-third said they had the right intentions but the wrong means. Only 15% were willing to describe them as just goondas.
Equally importantly, 50% of the respondents felt the Naxalites had forced the government to focus on development work in the affected areas. What these responses show is just how negative the perception of the government is in these parts.
In 2013, FirstPost.com reported on election results in Chhattisgarh:
More than two million voters -- or 67 percent of the electorate -- defied Maoists to vote in the first phase of Chhattisgarh's assembly elections that marked the start of the biggest popularity contest ahead of the Lok Sabha polls. Sporadic violence left a trooper dead.
This number included 60 percent turnout in Bastar, and 67 percent turnout in Dantewada, both of which are considered to be hotbeds of Naxal violence.
After Maoists called for a boycott of the exercise, ballotting began on a dull note. But polling rapidly picked up as the day progressed. About 30-35 percent had voted by afternoon.
By the time curtains came down, 67 percent of the 2.9 million voters involved in Monday's voting had exercised their franchise.
With Naxalites boycotting the election, I'd say a 67% turnout shows support for Naxalites is down, at least in the state of Chhattisgarh (which is also on Wikipedia's list of areas where Naxalites are active).
In 2018 business-standard.com reported interviews in rural Chhattisgarh. While it's not an opinion poll, the sentiment may be relevant. They found that interviewees were not satisfied with the government's actions in their area.
For example, they cited an 'us vs. them' mentality regarding deforestation:
“I heard in Delhi, the government planned to cut 1,700 trees, and the Supreme Court stopped them,” said Armo. “Do they even know what is going on here?” Next to him, Janandhan Singh Purte (38) joined in the conversation. “These trees have existed before us,” he said. “They gave us everything we needed. Now our grandchildren, their children and the generations after them will never know what it is like to grow under their shade.”
Discontent with the incumbent BJP lead one district to vote for the Indian Community Party while interviewees expressed wanting to vote BJP out no matter the alternative (so without naming Naxalites or communism):
With little to no development under the BJP for 15 years, locals near the Kanger Valley National Park in Dhurwa, in neighbouring Bastar district, pledged support for the CPI (Marxist). The densely forested area--notorious for the Jeeram Ghati Naxal attack of 2013 that killed more than 25 senior state Congress leaders--is riddled with land mines and no signs of the government.
“Neither the BJP nor Congress have bothered to come visit us for years now,” said Sanna Muchaki (27). “We are still waiting for a water hand pump. This village will only vote for the CPI (M)--only if they are given a chance, will we get our rights.”
In Sarguja and Surajpur districts, where villagers are alert to the land-mining conflict at their doorstep, most Adivasis we met appeared determined to vote the BJP out of power, regardless of the alternative.
I've not been able to find more recent surveys that answer your question. I did find some reports about how Covid hit in areas where Naxalism is more widespread but most of them don't cover how popular the movement is.
For further reading on the group, I'd suggest Dipak Gupta's Understanding Terrorism and Political Violence The Life Cycle of Birth, Growth, Transformation, and Demise which covers Naxalism as well as other movements (pre-covid) as recommended by Leiden University's Counterterrorism Bookshelf. More accessible is this article on deccanherald.com about Naxalists struggle during the pandemic.
