There is a twitter discussion and people are asking exactly that: how many people are at the moment allowed to push directly on the master branch?

I am creating this thread in response to the discussion occurring at https://bitcointalk.org/index.php?topic=1773558.msg17697805#msg17697805. This list will contain the names (or pseudonyms) of everyone who I can find evidence for ever having commit access to Bitcoin Core, the dates during which they had commit access, sources for all of this information, and reasoning for the access. Those who currently have commit access are in bold.

• Satoshi Nakamoto (satoshi, s_nakamoto): 2009-01-03 - 2011-09-13^[1] Creator, first Lead Maintainer
• Martti Malmi (Sirius, sirius_m): 2009-08-30 - 2011-09-13^[1][2]    Creator of first SVN repo
• Laszlo (laszloh) 2010-08-04 - 2011-09-131^[1]    Original OSX Builds and support
• Gavin Andresen (gavinandresen): 2010-10-11 - 2016-05-02^[3]    Frequent contributor; later Lead Maintainer
• Chris Moore (dooglus): 2011-01-21 - 2011-03-31    Frequent contributor for some time; Still occasionally contributes
• Pieter Wuille (sipa): 2011-05-01 - 2022-07-07    Frequent contributor
• Jeff Garzik (jgarzik): 2011-05-06 - July/Aug 2016 ^[4]    Frequent Contributor
• Wladimir J. van der Laan (laanwj, wumpus): 2011-06-05 - present^[5]    Frequent contributor; later Lead Maintainer
• Nils Schneider (tcatm): 2011-09-19 - 5/31/12    Frequent contributor for some time
• Greg Maxwell (gmaxwell): 2012-02-11 - 2015-12-17    Frequent contributor; Gave up commit access due to toxicity and drama from the community
• Jonas Schnelli (jonasschnelli): 2015-11-13 - 2021-10-21^[6]    Frequent contributor; given access after becoming GUI Maintainer; Stepped down for personal reasons
• Marco Falke (marcofalke): 2016-04-13 - present^[7]    Frequent Contributor; given access after becoming QA/Testing Maintainer
• Samuel Dobson (MeshCollider): 2018-12-06 - 2021-09-12^[8]    Frequent Contributor; given access after volunteering to be the wallet maintainer; Stepped down to focus on his PhD
• Michael Ford (fanquake): 2019-06-08 - present^[9]    Frequent Contributor; given access after being nominated by several other frequent contributors and maintainers to become a maintainer.
• Hennadii Stepanov (hebasto): 2021-04-19 - present  Frequent Contributor; given access after volunteering to help maintain the GUI
• Andrew Chow (achow101): 2021-12-20 - present^[10]     Frequent Contributor; given access after volunteering to be the wallet maintainer.
• Gloria Zhao (glozow): 2022-07-07 - presentt^[11]    Frequent contributor, given access after being nominated by several frequent contributors and maintainers to become a maintainer.

And how is this list controlled? What is necessary to add new people in the master-pushers and what is needed to remove someone?

Another interesting fact is that the giving out of commit access has become more strict. It is now a privilege held by those given maintainer positions and those whose privilege was grandfathered in (i.e. they had it previously and kept it, until otherwise revoked). Previously it was simply given out to those who contributed frequently and revoked after they stopped contributing. This appears to be no longer the case, although there are still multiple people who can commit to the repository so that there is not any reliance on one person. The maintainers are still given to frequent contributors as the maintainers are frequent contributors to the set of functionality for which they are maintainers of. They received the positions because of frequent contributions to those functionalities. Of those whose commit access was grandfathered, only Pieter Wuille remains - the rest were revoked eventually primarily for the lack of contributions (see each individual for their specific reason).