Here's a question: are there more people alive than dead? Well, the population is certainly higher now than it's ever been, and it's increasing by the birth rate minus the death rate. The number of dead people is increasing by the death rate. So, if (birth - death) > (death) on average throughout all history then there are more living people than dead people. It seems unlikely that the birth rate has been, on average, twice the death rate, and the standard demographic transition model reflects that for most of history both the birth and death rates have been very high.
Only in the transition stages (2 and 3) is the birth rate much higher than the death rate, so in my estimation there are probably far more dead people than living people.
# Stage 1, the situation that has characterized the world throughout most of history, is marked by high death and birth rates. Population levels fluctuate somewhat but there is no steady growth.
# In Stage 2, which began in the West around 1800, birth rates remain steady but mortality rates begin to decline because of improvements that reduce the toll of infectious diseases--the big killer in countries with high death rates. Population begins to grow.
# In Stage 3, a continuing decrease in death rates is accompanied by a decline in birth rates. Falling childhood mortality means that the number of births
needed to reach a desired family size drops. In response, fertility rates decline, but the population continues to grow because the number of births in a society is based not only on the number of children each woman bears but also on the number of women of childbearing age. With a disproportionate share of people in the childbearing years, population grows even after fertility rates decline.
# In Stage 4, the situation in the developed world today, there is a rough parity between births and deaths. Correspondingly, the population grows very slowly--if at all. Once a Stage 4 equilibrium of low birth and death rates is reached, immigration becomes the driving force for additional population growth.