Here’s some excerpts of a 2020 interview where he talks about Gonzalo:

The people’s war in Peru broke out in the early 1980s as an exceedingly happy and inspiring event for the proletariat and people not only in Peru but in the whole world in the face of dismal events, such as the Dengist counterrevolution and capitalist restoration in China adding up to the continuing degeneration of Soviet modern revisionism and to the self-defeating adventures of Soviet social imperialism.

But I think that certain problems or errors afflicted the party leadership and revolutionary movement and made them decline in the course of their ten years of armed struggle, especially after the capture of Abimael Guzman. But it is up to the proletarian revolutionaries of Peru to do their criticism and rectification of errors, even as many revolutionary observers have noted that the Gonzalo leadership had been ultra-Left sectarian and failed to use the united front fully as one more weapon in the course of the people’s war and that after his capture he swung to the Right by toying with peace negotiations as his possible way out of prison, with no safeguards against confusing the revolutionaries and the masses. […]
It is to the credit of the CP of Peru and the RIM that they were ahead of all other entities in using the label Maoism to supplant Mao Zedong Thought. But they were not only for the symmetry of Maoism in relation to Marxism and Leninism. They claimed that in adopting the label of Maoism they were determining and defining its content to shame all other CPs for being off the line by not using the term Maoism. Worst of all, Gonzalo or the CP of Peru adopted the phrase, Gonzalo Thought, with the immodest claim that the phrase signified his own definition of Maoism as the third stage of Marxism-Leninism and his Thought as the brilliant further development, despite the fact that he had not yet won total victory in the Peruvian revolution. […]

To this day, CPP frowns on the immodest practice of certain parties naming their guiding theory after their principal leaders, like Gonzalo Thought, Prachanda Path and Avakian’s New Synthesis. These labels are immodest and are manifestations of puerile idolatry and the leaders’ own self-indulgence and self-glorification. Communists should selflessly do the best they can to wage and advance the revolution and forget about seeking personal fame or claiming for oneself the credit that belongs to the revolutionary forces of the proletariat and the people. It was not Marx and Lenin themselves who labelled their collection of ideas and actions with their respective names.

I found another text supposedly describing his opinions about Gonzalo, but I wasn’t able to fully verify:

He made a most balanced appraisal of late Chairman Gonzalo and the peoples War in Peru and analytically summed up the anti-Marxist nature of the Revolutionary Internationalist Movement. He summed up the anti Marxist nature of Gonzalo’s writings on ‘militarisation of the party’ and ‘Peoples War Till Communism.’ Sison analysed PCP’s wrongly evaluating stage of strategic equilibrium and prematurely fusing urban armed actions with people’s war. He refuted Gonzoliate sections who advocated that protracted peoples war was a universal theory, applicable also to imperialist countries.