This study investigates the role of large-team collaboration in shaping early-career scholars' career development, with a focus on gender disparities. Using publication and collaboration data from SciSciNet in Computer Science, we capture the social capital accumulation process in academia with a neighborhood-based centrality metric and publication counts. Synthetic difference-in-differences (SDID) is applied to estimate the impact of early experience in large-team collaboration on subsequent research careers. Results indicate that junior scholars participating in large-team research significantly improve their network centrality, indicating more frequent collaborations with influential scholars, and produce approximately 0.75 more publications per year. Meanwhile, we document persistent gender gaps: men are 16% more likely to access large-team collaborations. These findings highlight large-team collaboration as both a source of career acceleration and a mechanism of gender inequality. We conclude with implications for equity promotion and strategies enabling more inclusive collaboration.