A person who conducts or analyses opinion polls.
It's how Lexico defines the word 'pollster'. However, this page suggests the term may be applied to polling organizations as well. May it?
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pollster NOUN COUNTABLE
a person or organization that prepares a poll
Pollster (Macmillan Dictionary)
A word used for a person who does a job can often be used for a company or organisation (British spelling) that does it - e.g. grocer, tailor, butcher, baker, carmaker, shipbuilder, builder.