We report new measurements of the branching fraction B (Ds+ → ℓ+ν), where ℓ+ is either μ+ or τ+ ( → π+ ντ), based on 6.32 fb−1 of electron-positron annihilation data collected by the BESIII experiment at six center-of-mass energy points between 4.178 and 4.226 GeV. Simultaneously floating the Ds+ → μ+ νμ and Ds+ → τ+ ντ components yields B (Ds+ → τ+ ντ) = ( 5.21 ± 0.25 ± 0.17 ) × 10−2, B (Ds+ → μ+ νμ) = ( 5.35 ± 0.13 ± 0.16 ) × 10−3, and the ratio of decay widths ..., where the first uncertainties are statistical and the second systematic. No evidence of CP asymmetry is observed in the decay rates Ds± → μ± νμ and Ds± → τ± ντ : ACP (μ± ν) = (− 1.2 ± 2.5 ± 1.0) % and ACP (τ± ν) = ( + 2.9 ± 4.8 ± 1.0)%. Constraining our measurement to the Standard Model expectation of lepton universality (R = 9.75), we find the more precise results B (Ds+ → τ+ ντ) = ( 5.22 ± 0.10 ± 0.14 ) × 10−2 and ACP ( τ± ντ) = ( − 0.1 ± 1.9 ± 1.0 )%. Combining our results with inputs external to our analysis, we determine the c →s quark mixing matrix element, Ds+ decay constant, and ratio of the decay constants to be | Vcs | = 0.973 ± 0.009 ± 0.014 , fD+s = 249.9 ± 2.4 ± 3.5     MeV , and fD+s / fD+ = 1.232 ± 0.035, respectively.