Generally, it is special invitees holding officially issued viewing cards who can watch live.
In addition, the parade invites a lot of crowd participation.
According to the official Xinjing Newspaper on Sept. 25 (web link):
The event will consist of 100,000 people, 70 groups of colorful vehicles in 36 squares and three situational marches that will pass through the core area of Tiananmen Square along Chang'an Street from east to west. With "free, vivid, joyful, lively" form of emotional expression. It consists of a prologue, a main body and an epilogue, and the main body is divided into three parts: "Founding of the Nation", "Reform and Opening Up", and "Great Rejuvenation", with a total duration of about 65 minutes.
Time: the morning of October 1, 2019
Number: more than 100,000 people from all walks of life
Objects: Covering all walks of life and all ethnic groups, including representatives of the masses in all fields such as workers, peasants, teachers, students, doctors, civil servants and other representatives of the masses, as well as courier boys, square dance mothers, new social strata people and other emerging fields. It also includes representatives of people from emerging fields such as courier boys, square dancers and new social strata, as well as representatives of compatriots in Hong Kong, Macao and Taiwan, overseas compatriots and foreign friends.
Additionally, the commemorative meeting and military parade also invited more than 30,000 ordinary people, including representatives of the families of ordinary citizens in Beijing, ordinary laborers, including some representatives of migrant workers to participate in the ceremony.